Exploring the Exterior Angle Theorem

Mr. Duggal introduces the exterior angle theorem, explaining that the exterior angle of a triangle equals the sum of the two opposite interior angles. He demonstrates this with examples, showing how to apply the theorem to solve problems involving missing angles in triangles. The video covers the basic proof of the theorem and its practical applications, providing a solid foundation for understanding and using the exterior angle theorem in geometry.

What is the main topic discussed in the video?

• Angle Bisector Theorem

• Pythagorean Theorem

• Exterior Angle Theorem

• Interior Angle Theorem

What is the sum of the angles in a triangle?

• 270 degrees

• 360 degrees

• 90 degrees

• 180 degrees

If one angle of a straight line is 70 degrees, what is the measure of the other angle?

• 70 degrees

• 90 degrees

• 180 degrees

• 110 degrees

In the blue triangle example, if one interior angle is 72 degrees and another is 38 degrees, what is the measure of the exterior angle?

• 180 degrees

• 110 degrees

• 38 degrees

• 72 degrees

What is the measure of the exterior angle in the red triangle example if the two opposite interior angles are 63 degrees and 39 degrees?

• 102 degrees

• 39 degrees

• 180 degrees

• 63 degrees

In the red triangle example, what is the measure of the third angle if the exterior angle is 102 degrees?

• 78 degrees

• 102 degrees

• 39 degrees

• 63 degrees

How can the exterior angle theorem help in finding two missing angles of a triangle?

• By using the sum of all angles in a triangle

• By using the supplementary angles

• By using the exterior angle and one interior angle

• By using the exterior angle and the two opposite interior angles

If the exterior angle is 42 degrees and one of the opposite interior angles is 71 degrees, what is the measure of the other interior angle?

• 71 degrees

• 67 degrees

• 42 degrees

• 113 degrees

What is the measure of the exterior angle if the two opposite interior angles are 71 degrees and 42 degrees?

• 113 degrees

• 71 degrees

• 180 degrees

• 42 degrees

What is the key takeaway from the video about the exterior angle theorem?

• The exterior angle is always equal to the supplementary angle

• The exterior angle is always equal to the sum of all interior angles

• The exterior angle is always equal to the sum of the two opposite interior angles

• The exterior angle is always equal to one of the interior angles