Cara menentukan besar sudut pada sudut berpenyiku berpelurus dan bertolak belakang

Summary

In this educational video, the presenter explains how to calculate angles in geometry, specifically focusing on angles that are supplementary or vertically opposite. Through several examples, the video demonstrates step-by-step methods for determining unknown values of 'x' in angle equations. Key concepts like complementary angles and the relationships between angles on a straight line are covered. The video is designed to make the process of solving angle-related problems accessible and easy to understand, offering clear explanations and practical examples. The presenter encourages viewers to like, subscribe, and share the video for more educational content.

Takeaways

• 😀 The video teaches how to determine the size of angles in various geometrical situations, specifically with angles that are supplementary or opposite.
• 😀 The first example involves calculating the value of 'x' using the relationship between two angles that are supplementary (sum to 90 degrees).
• 😀 In the first problem, the sum of angles ABD and DBC is 90 degrees, and solving the equation leads to finding x = 23.
• 😀 After finding x, the angle ABD is calculated as 54 degrees by substituting x into the given expression for the angle.
• 😀 The second example discusses finding the value of x in a situation where two angles are supplementary and sum to 180 degrees.
• 😀 In the second example, the sum of angles ABD (2x + 5) and DBC (3x - 10) is 180 degrees, leading to x = 37.
• 😀 After solving for x, the angle DBC is calculated to be 101 degrees by substituting x = 37 into the given expression for the angle.
• 😀 The third example involves finding the value of x for two angles that are opposite each other, meaning they are equal in size.
• 😀 In the third problem, the equation 2x + 7 = 3x - 42 is solved by moving terms around, leading to x = 49.
• 😀 After finding x, the angle ABC is calculated to be 105 degrees by substituting x = 49 into the given expression for the angle.
• 😀 The video concludes by encouraging viewers to like, subscribe, and share the video if they found it helpful, while also offering an apology for any shortcomings in the content.

Q & A

What is the main topic of the video?

The main topic of the video is about determining the size of angles in various geometric situations, including angles formed by intersecting lines and angles that are complementary or supplementary.

How is the first example in the video solved?

In the first example, we are given the angle ABD as '2x + 8'. Using the fact that angle ABD and angle DBC are complementary (add up to 90 degrees), we set up an equation: '2x + 8 + x + 13 = 90'. Solving for x, we find that x = 23, and substituting x into the angle formula gives the angle ABD as 54 degrees.

What property of the angles is used in the second example?

In the second example, the property used is that the sum of two angles that are supplementary (form a straight line) equals 180 degrees. The equation '2x + 5 + 3x - 10 = 180' is solved to find x = 37, and the angle DBC is calculated to be 101 degrees.

Why are angles ABD and DBC considered complementary in the first problem?

Angles ABD and DBC are complementary because they form a right angle (90 degrees) when combined. This is a key property of complementary angles.

How is the value of x determined in the second example?

To determine the value of x in the second example, the equation '2x + 5 + 3x - 10 = 180' is simplified and solved. After simplifying, we get '5x - 5 = 180'. Adding 5 to both sides gives '5x = 185', and then dividing both sides by 5 results in x = 37.

What does the term 'berpelurus' mean in the video?

'Berpelurus' refers to angles that are supplementary, meaning they form a straight line and sum to 180 degrees.

What is the key step in solving the third example in the video?

In the third example, the key step is recognizing that angles ABC and EBD are opposite angles (vertically opposite), meaning they are equal in value. The equation '2x + 7 = 3x - 42' is set up and solved for x, which gives x = 49. Substituting x into the equation for angle ABC gives the final result of 105 degrees.

What is the relationship between the angles ABC and EBD in the third example?

Angles ABC and EBD are vertically opposite angles. According to the property of vertically opposite angles, they are always equal in size.

Why is the equation '2x + 7 = 3x - 42' used in the third example?

The equation '2x + 7 = 3x - 42' is used because angles ABC and EBD are vertically opposite, and therefore, they are equal in size. This equation sets their sizes equal to each other, and solving it helps determine the value of x.

What is the final result for angle ABC in the third example?

After solving for x = 49, we substitute this value back into the expression for angle ABC, which gives '2 * 49 + 7 = 98 + 7 = 105 degrees'. Therefore, the size of angle ABC is 105 degrees.