How to calculate circle skirt radius/Detailed explanation on how to cut circle skirt.
Summary
TLDRIn this 'All About Sewing' lesson, the instructor teaches viewers how to calculate the radius for different degrees of circle skirts, including 360, 270, 180, and 90-degree styles. The key formula involves dividing the waist measurement by 6.28, with adjustments for skirt degree and fabric stretch. The tutorial simplifies the math, making it accessible for sewing enthusiasts to create full, half, quarter-circle skirts, and more, with practical tips for fabric cutting and fitting.
Takeaways
- 📐 The lesson focuses on calculating the radius for different types of circle skirts using specific formulas.
- 🧵 For a 360-degree full circle skirt, the radius is found by dividing the waist measurement by 6.28.
- 🔄 The 360-degree skirt forms a full circle, with the radius being the distance from the waist to the hem.
- ✂️ To get a perfect fit for non-stretch fabric, subtract 2 inches from the waist measurement before dividing by 6.28.
- 📏 A 270-degree skirt uses a similar method but with an additional factor of 1.33 in the formula.
- 💡 The 1.33 factor comes from dividing three-quarters of a full circle (3/4) to adjust the formula for a 270-degree skirt.
- ➗ For a 180-degree half-circle skirt, divide the waist measurement by 3.14 to find the radius.
- 🔍 The 180-degree formula simplifies the full circle formula by considering half of the circle's circumference.
- 🔄 A 90-degree quarter-circle skirt requires multiplying the waist measurement by 2 and dividing by 3.14 to find the radius.
- 🧮 Each formula is derived from the basic concept of calculating the circumference of a circle, adapting it to different skirt designs.
Q & A
What is the primary focus of the 'All About Sewing: Circle Skirt Lesson One'?
-The primary focus of the lesson is to teach the mathematics involved in creating circle skirts, specifically the formula for calculating the radius needed for different degrees of circle skirts.
What is the formula used to calculate the radius for a 360-degree circle skirt?
-For a 360-degree circle skirt, the formula to calculate the radius is to divide the waist measurement by 6.28.
Why might you need to subtract 2 inches from the waist measurement when sewing a stretch fabric circle skirt?
-You might need to subtract 2 inches from the waist measurement when sewing a stretch fabric circle skirt to ensure a perfect fit around the waist without needing any side or back seams or zippers.
What is the significance of the number 6.28 in the context of the sewing lesson?
-The number 6.28 is used in the formulas because it represents two times pi (2π), which is the constant used to calculate the circumference of a circle.
How does the formula for a 270-degree circle skirt differ from that of a 360-degree skirt?
-For a 270-degree circle skirt, the waist measurement is multiplied by 1.33 and then divided by 6.28, as opposed to just dividing by 6.28 for a 360-degree skirt.
What mathematical concept is used to derive the radius for a 180-degree circle skirt?
-The radius for a 180-degree circle skirt is derived by dividing the waist measurement by 3.14, which is half of 6.28, representing half of the full circle's circumference.
Why is the number 3.14 used in the formula for a 180-degree circle skirt?
-The number 3.14 is used because it represents π, and since a 180-degree circle skirt is half of a full circle, the formula uses half of 6.28 (which is 2π).
What is the formula for calculating the radius of a 90-degree circle skirt?
-For a 90-degree circle skirt, the formula is to multiply the waist measurement by 4 and then divide by 6.28, or alternatively, divide the waist measurement by 3.14 after considering the full circle formula.
How does the instructor explain the transition from the full circle formula to the half and quarter circle formulas?
-The instructor explains the transition by demonstrating how the full circle formula is adjusted by dividing by 2 for the half circle (180 degrees) and by 4 for the quarter circle (90 degrees), reflecting the proportional parts of the circle being used.
What additional advice does the instructor give for cutting out the circle skirt pieces from the fabric?
-The instructor advises that for non-stretch fabrics, the material should be folded into four to cut out the circle, and for stretch fabrics, one might need to adjust the waist measurement accordingly to avoid seams or zippers.
Outlines
🧵 Introduction to Circle Skirt Math
This paragraph introduces the concept of sewing a circle skirt, focusing on the math needed to cut the skirt correctly. The instructor reassures viewers that the math is simple and involves a specific formula for dividing the waist measurement to find the radius, which is crucial for cutting the skirt. The example given is for a 360-degree circle skirt, also known as a full circle skirt, where the radius is calculated by dividing the waist measurement by 6.28. The paragraph also touches on considerations for stretchy and non-stretchy fabrics and the potential need for subtracting two inches from the waist measurement for a perfect fit.
📏 Calculating the Radius for a 360-Degree Circle Skirt
This section dives into the calculation of the radius for a 360-degree circle skirt, using a basic mathematical formula. The circumference of the circle is represented by the waist measurement, and the radius is derived by making it the subject of the formula. The instructor explains that the circumference is equal to 2πr (where π is 3.14), and by rearranging the formula, the radius is found by dividing the waist measurement by 6.28. The explanation is reinforced by reworking the formula step-by-step, clarifying how this math is applied in the context of sewing.
🔄 Understanding the 270-Degree Circle Skirt
This paragraph discusses the 270-degree circle skirt, highlighting the difference in its formula compared to the 360-degree skirt. The main distinction is the introduction of a factor of 1.33, which comes from dividing the circle into four parts and using three of those parts. The instructor explains how this factor alters the formula, which now requires multiplying the waist measurement by 1.33 before dividing by 6.28. The instructor also promises further explanation in a later lesson, particularly regarding the practical aspect of cutting a 270-degree circle skirt.
➗ Calculating the Radius for a 180-Degree Circle Skirt
This section covers the 180-degree circle skirt, where the full circle is divided into two halves. The formula to calculate the radius for this type of skirt is slightly modified: the waist measurement is divided by 3.14 instead of 6.28. The instructor provides a detailed mathematical explanation, showing how the full circle formula is adapted by dividing both the numerator and denominator by two, leading to the simplified formula used for the 180-degree skirt. The importance of understanding this change in the formula is emphasized.
🔢 Formula for a 90-Degree Circle Skirt
The final paragraph discusses the 90-degree circle skirt, which is essentially a quarter of a full circle. The radius for this skirt is calculated by dividing the waist measurement by 3.14 after adjusting the full circle formula. The instructor explains how the full circle formula is adapted by multiplying the waist measurement by four and then dividing the result by 6.28, which simplifies to dividing the waist measurement by 3.14. The instructor reassures viewers that these formulas are easy to understand and will be further demonstrated in upcoming lessons.
Mindmap
Keywords
💡Circle Skirt
💡Skirt Math
💡360 Degree Circle Skirt
💡Radius
💡Waist Measurement
💡Non-Stretch Fabric
💡Stretch Fabric
💡Joining
💡Zip
💡270 Degree Circle Skirt
💡180 Degree Circle Skirt
Highlights
Introduction to the circle skirt lesson focusing on skirt math.
Explanation of the formula for a 360-degree circle skirt, also known as a full circle skirt.
The importance of calculating the radius for cutting the skirt.
How to divide the waist measurement by 6.28 to get the radius for a 360-degree skirt.
Instructions for adjusting the waist measurement for stretch fabrics.
The difference between waist measurement adjustments for stretch and non-stretch fabrics.
Visual demonstration of the full circle skirt's shape and fit.
Introduction to the 270-degree circle skirt and its formula.
Explanation of the 1.33 multiplier in the 270-degree skirt formula.
The 180-degree circle skirt's formula and its relation to the full circle.
How to calculate the radius for a 180-degree skirt using waist measurement divided by 3.14.
Introduction to the 90-degree circle skirt and its formula.
Calculation method for the radius of a 90-degree skirt using waist measurement divided by 3.14.
Overview of the four types of circle skirts: 360, 270, 180, and 90 degrees.
The significance of the number 6.28 in the formula and its relation to pi.
A brief explanation of the mathematical formula for the circumference of a circle.
How to derive the radius formula from the circumference formula.
Conclusion and invitation for questions, signaling the end of the lesson.
Transcripts
hi everyone welcome to all about sewing
circle skirt lesson one in this lesson
i'm going to teach you second skirt math
so a lot of people
math is just like doing a magic but
trust me it is really really easy all
you need to know is the formula for a
particular skirt you're cutting so for
example you're cutting a 360 degree
circle square you need to know what to
use to divide your waist measurement to
get the radius for you to be able to cut
the skirt so let's get started
for
360
the grey sapper skirt which is also
known as a full circle skirt of fufule
which is
like this
there's a full round circle so here you
have to get your radius
this from this point to this point is
the radius so the full
middle part here is the diameter but all
we need to know is the radius which is
from the middle to the end point here so
this is going on the waist
and this is the lower part of the skate
so here when you fold your material into
four so all you need to do is from this
tip
all around to get the radius for you to
be able to cut out this little circle
inside
for this part to go on the waist so for
360
circle
skirt
to get your radius you have to do
your waist measurement let me use m to
represent measurement your waist
measurement divided by
6.28
so this is what you use to get the
radius here to be able to cut out the
little
circle inside so this is on the lower
part of your skin and this is going
around your waist
note that
on this part of your skin is stretchy
even for non-stretch fabric so if you
don't want to have any joining on the
side or on the back for zip if it's a
stretch fabric you need to minus two
inches
from your waist measurement
here so
to have that perfect fit around the
waist so you need to minus two from your
waist measurement but if you're having a
joining maybe on the side or on the back
side for zip you don't have to minus
this two inches
from your waist measurement
so
here this is how the skate looks like
it's very full
and it goes like
it's very very very full
goes like this so this part is what we
have here in the middle so it's just
like a circle
so this is 360 degree second square
which is a full circle scale so we have
three more we have the 270 degree we
have the 180 degree and we also have the
90 degree so which makes it
four types of
circle skate we have and the most common
ones is always the 360 and a 180
so remember that this two inches you're
deducting from your waist measurement is
before dividing with the 6.28
so
if you're if you're not for example if
say you're joining on the side or at the
back you don't have to
minus this
to from your waist measurement so you
just use your waist measurement divided
by 6.28 so if you care to know how this
6.2 a
came into this formula
so this is a circle and the second
friends of the circle that is the
measure around the circle
so the second french of this little
circle we are cutting out equals two pi
r so that is the math formula of finding
the circumference of a circle so
basically this is a circle and we want
to know the radius here
so this is the radius
so pi is always this is constant is
always 3.14 or 22 over seven so
this is pi and it's constant
here
okay sorry brother okay so set the
second friends of the circle will be two
multiplied by this three point one eight
it won't force sorry three point one
four
multiply by this r you're having here
okay
so
let me erase this
okay
so here
i have 2 multiplied by 3.14 that will
give me
6.28
so c equals
6.28
then remember this r
so now
we're looking for the r
so we need to make this r the subject of
this formula
so here i have the r i'm bringing a har
as the subject of the formula so i'm
dividing both sides if i divide both
sides by two point six point two eight
divided by six point two eight so this
six point two eight is going to cancel
this this is just a basic max don't get
confused so you're left with r here
then equals the c
which is the circumference of the circle
divided by
6.28
so this is just a basic mass so
this c is represent this c is the
circumference of this circle which is
the same as our waist measurement so
that is why
in this formula
the c here is replaced with this the
waist measurements divided by the same
6.28
i hope you understand that but let me
quickly go over it again so this is the
second friends of the circle the little
circle we are cutting out from the scale
to go on the waist
so that is circumference of the circle
so which is c to represent the second
friend equals two pi r this is the
formula of finding of circumference of a
circle so here pi is always
3.14
okay so i replace this pi with 3.14 here
so 2 multiplied by 3.1 for r
so i have it here to be 2 multiplied by
3.14 so that gave me 6.28
then i
i put in this heart here so i have c
equals that is the circumference of the
circle equals
6.28 multiplied by the radius
so here how can i make the r the subject
of the formula so here what i'm going to
do is divide both sides by 6.28 because
i want to get rid of this 6.28 beside
the heart and make this r stand alone
so when i divide when i divided both
sides by 6.28 this 6.28 i have here
cross out the 6.28 beside the r so i'm
left with c over 6.28 equals r which is
the same thing as r
as the radius equals circumference
divided by 6.28
and this is replaced with waist
measurement because that is the part
that is going on
the waist
the next one is 270 degree
second skirt
okay so 4270 as i mean i have a line
going through the side so i have just
this spot
for the 270.
so guys
before we have 360. that's 1990 9090 so
990 is 180 then close the
other 90 degree we have
270
so here
yes so the radius is just going to be
from here
to this side
like this one
okay so that is for 270 degree
circle
skirt
okay
so here
it's very similar to the full one the
difference is just this back so
here i have
the radius to be
1.33
multiplied by your waist
measurement
then divided by
6.28 so the only difference we have here
is just this
1.33
so if you can't know how is 1.33 came
into this formula so we have this is
just
three over four
so which is if i divide this the former
circle into four i have one
two three four so now i'm having three
out of four that is three over four
so now you're dividing your waist
measurement
by three over four
here and then when you multiply
this way
this changes so the denominator comes up
and
the numerator goes down that is the
basic mass don't worry yourself too much
about this so you have your waist
multiplied by
4 over 3 and when you calculate 4 over 3
you have
1.33
so that is how this 1.33 came into this
formula by dividing 4 into 3
so that is 1.33 so after calculating
this for your radius
you're doing that for the old circle
after which you have to remove one out
of
those four
i'll explain more on this how you can
cut this to 270 degree circle scale in
the for of i think thought lesson yeah
or the thought lesson
so that is that about 270 degree this is
just the difference in the formula from
the previous one we had
so that this is the 270 degree formula
moving on to 180 degrees circle
so 180 degree
circle skirt
okay
so here we are dividing the whole this
is let me draw the full circle again so
we are dividing this full circle into
two
so
so the radius i'm having from here to
here or from here to here
so this is just the radius here
so from
here to here
okay
so
for this 180 degree
circle skirt
remember for the full one we had a
circumference equals
the waist measurement divided by
6.28
okay but here this
full circle is divided by two that is
half
of the full
second friends we had
okay so here
that is
we divided the circumference into two so
now to get the formula for this 180 we
need to multiply it by the
circumference to get this part of the
circle
if we want to divide
we want to use the circle the
circumference formula so here
when we want to multiply this as usual
the denominator comes up and the
numerator comes down that is 2 over 1
and 2 over 1 is same thing as 2.
multiply by the waist
then
that would be divided by 6.28
let me do that again
so for the 180 here
i have
the radius equals
to
multiply by
the waist
measurement
then divided by
6.28
this
still the number
the waist measurement divided by two
6.28 we had in the previous step
so the only difference
on this
180 degree is that
you have
two of this f
in the o circle
so this is still the formula of the full
circle but this is just telling us that
we have two of this
on the half so
when
you cross half two goes here in one and
six point two eight divided by two you
have three point
one four
so if you didn't really get that don't
worry this is just a basic maths so it's
just that i'm dividing i have to hop
here and i have 6.28 here so instead of
repeat repeating this like saying my
waist measurement multiply by two and
divide this which i know i can divide
this
6.28 by two and get rid of those two i
have on the upper part here so it's just
basically saying i divided this by two
and also i divided this by two so here i
have
these two is gone so i have my waist
measurement
sorry
so here i have my waist measurement
divided by 3.14
so if you don't really understand these
steps just note that
for 180 degree circle scale
to find the radius you're using your
waist measurement
divided by 3.14
so the explanation i did earlier is just
for you to understand how this
3.14 was changed from the number 6.28 we
use for the full circle that is because
we have this half circle twice
in the full circle so that is just the
basic my about 180 degree circle
moving on to 90
degree circle which is the last one
so here
as i mean i okay let me draw the full
circle again
sorry this is not all right okay
so imagine if i want to divide my circle
into four and i'm having just this 90
remember this is 360 and
if i remove one of it that's -90 i have
270
then if i remove one again i'm left with
180 and then if i remove okay let me
remove this part
okay here i'm left with 90 degree
so here this is the little
circle we're cutting half to the radius
we just be from this point down to
so the radius is just going to be from
this point to this point
and this point so this is the eye
here
okay so this is 90 degrees
spirit
okay
so
for this this is just like saying we
divided the whole second friends into
four so to get this
using the we're still using the full
circle formula but we're going to
multiply
out this part by four if we still want
to maintain
the full
circle formula so here if i have
4
[Music]
so basically this is just telling me
that
4 of this will give me the full
circle which i'm using the formula so 4
multiplied by my waist measurement
divided by 6.28
so i'm still using a full circle formula
but this four is
telling me that i have
four of these 90 in the full
circle formula i'm using so i have just
this
as 90 but that would give me four times
this whole circle to be able to get 360
because i'm seizing
here i'm see using the full circle so
this is just like saying
four out of the four circle
so here
like the 180 where i have two up here
and six point two eight a then i divided
both by two so same thing i can divide
by two i can't divide this by four but i
can divide it by two so if i divide four
by two i'm left with two and if i divide
this by two i'm left with three
point one four
so
using this
my radius will be
two remember i have two here
that is i had four before
when i divided by two that gave me
2. so i have to
multiply by my waist
measurement
then divided by not 6.28 this time but
3.14 because i divided both my numerator
here by two and the denominator also by
two so i'm having three point
one four
so this is
the formula for finding the radius of 90
degree
circle skirt
so just take note of all the formulas
they're easy
and
they're very very easy to understand if
you can just
put them in mind and take note of all
the formulas
i'll explain more next lessons how
radius is marked on fabric so when we're
doing the practical of cutting all the
degrees of sacrifice care we have so
that's all for today thank you
and let me know if you have any
questions
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