Perimeter of Composite Figures - Grade 4: Q1- Lesson 7 MATATAG Curriculum

Summary

In this educational video, viewers learn how to find the perimeter of composite figures made up of triangles and quadrilaterals. The video explains the concept of perimeter and demonstrates how to calculate the perimeter by adding up the outer sides of combined shapes. Through examples, viewers see how to determine missing measurements and find the perimeter of various composite figures. Additionally, the video includes a word problem to apply the concept and ends with an activity for practice. It emphasizes the importance of focusing only on the outer sides when calculating the perimeter.

Takeaways

• 😀 Perimeter is the total distance around a closed shape, calculated by adding the lengths of all its sides.
• 😀 Composite figures are made up of two or more simple geometric shapes like triangles and quadrilaterals.
• 😀 To find the perimeter of a composite figure, you need to add up the lengths of all the outer sides, excluding any shared sides.
• 😀 In composite figures, missing sides can be determined by using logical reasoning based on the given sides and their relationships.
• 😀 For example, if two sides of a composite figure are equal, the unknown side can be deduced based on symmetry.
• 😀 A composite figure can be broken down into smaller shapes like rectangles, squares, or triangles to simplify the perimeter calculation.
• 😀 The perimeter of a composite figure is the sum of all the outer sides, as demonstrated in examples like a rectangle attached to a triangle.
• 😀 When working with composite figures, ensure to calculate and sum the individual sides carefully to avoid errors.
• 😀 Word problems involving composite figures require logical steps to find missing sides, and then sum all the sides to find the perimeter.
• 😀 It's essential to understand the structure of composite figures and apply basic arithmetic and geometric principles to calculate their perimeter.

Q & A

What is the perimeter of a composite figure?

The perimeter of a composite figure is the total distance around the figure, calculated by adding the lengths of all its outer sides.

What are composite figures?

Composite figures, also known as compound shapes, are shapes made up of two or more simple geometric figures like triangles, rectangles, squares, or other polygons that are combined to form a more complex shape.

How do you find the perimeter of a composite figure?

To find the perimeter of a composite figure, you first identify the lengths of all the outer sides of the figure and add them together. Ensure you don't count any shared or internal sides.

What does it mean when the script mentions 'missing sides'?

Missing sides refer to sides of the composite figure that are not directly given in the problem. These can be calculated by using the relationships between known sides, such as subtraction or symmetry.

How do you calculate a missing side when two sides have equal measurements?

When two sides have equal measurements, such as the top and bottom sides of a rectangle, the missing side can be determined by using the given length of one side and applying symmetry, meaning the other side has the same measurement.

In the example with the composite figure made up of a rectangle and triangle, how is the missing side calculated?

In this example, the missing side is determined by recognizing that the top and bottom sides are equal in length. Therefore, the missing side is the same length as the opposite side, which helps complete the calculation of the perimeter.

What are the key steps in solving perimeter problems with composite figures?

The key steps include identifying all the outer sides, calculating any missing sides using given information or geometric relationships, and then adding all the side lengths together to get the perimeter.

Why is it important not to count internal sides when calculating the perimeter?

It is important not to count internal sides because the perimeter refers only to the outer boundary of the figure. Internal sides are not part of the perimeter and would lead to an incorrect calculation if included.

How do you approach a word problem involving the perimeter of composite figures?

To solve a word problem, first draw or visualize the composite figure, identify the known and unknown measurements, calculate any missing sides, and then sum up all the outer sides to find the perimeter.

What is the perimeter of a composite figure made up of a square, rectangle, and triangle in the example?

The perimeter of the composite figure made up of a square, rectangle, and triangle is 32 meters, calculated by adding the lengths of all the sides after determining the missing measurements.