Exploring the Exterior Angle Theorem

The video tutorial focuses on the exterior angle theorem, explaining that the measure of an exterior angle of a triangle equals the sum of the two remote interior angles. The lesson includes definitions, examples, and problem-solving techniques to determine missing angle measures in triangles. By the end of the lesson, students should be able to apply the theorem to solve for unknown angles.

What is a theorem?

• A guess

• A rule that works every time given specific circumstances

• A rule that works sometimes

• A hypothesis

Tags

CCSS.HSG.CO.C.11

What does the Exterior Angle Theorem state?

• The measure of an exterior angle of a triangle equals the sum of the two adjacent interior angles

• The measure of an exterior angle of a triangle equals the sum of the two remote interior angles

• The measure of an exterior angle of a triangle is always 180 degrees

• The measure of an exterior angle of a triangle is always 90 degrees

Tags

CCSS.8.G.A.5

Which of the following is an exterior angle?

• An angle inside the triangle

• An angle outside the triangle but connected to it

• An angle that is not connected to the triangle

• An angle that is equal to 90 degrees

Which angles are considered remote interior angles?

• The two angles outside the triangle

• The two angles inside the triangle

• The two angles opposite the exterior angle

• The two angles adjacent to the exterior angle

Tags

CCSS.8.G.A.5

If the exterior angle is 122° and one remote interior angle is 90°, what is the measure of the other remote interior angle?

• 32°

• 42°

• 52°

• 62°

Tags

CCSS.8.G.A.5

What is the measure of a straight line?

• 180°

• 90°

• 270°

• 360°

Tags

CCSS.4.MD.C.5B

CCSS.HSG.CO.A.1

If the two remote interior angles are 21° and 34°, what is the measure of the exterior angle?

• 55°

• 75°

• 45°

• 65°

Tags

CCSS.8.G.A.5

What is the first step in solving for a missing angle using the Exterior Angle Theorem?

• Identify the exterior angle

• Identify the remote interior angles

• Add the remote interior angles

• Subtract the remote interior angles

Tags

CCSS.8.G.A.5

If the exterior angle is 129° and one remote interior angle is 54°, what is the measure of the other remote interior angle?

• 95°

• 85°

• 75°

• 65°

Tags

CCSS.8.G.A.5

What should you do after solving for the measure of angle one?

• Check if the sum of all angles in the triangle is 180°

• Check if the sum of all angles in the triangle is 90°

• Check if the sum of all angles in the triangle is 270°

• Check if the sum of all angles in the triangle is 360°

Tags

CCSS.8.G.A.5