September 15th: Exterior Angle Theorem & Base Angle Theorem

Front

What is the Exterior Angle Theorem?

Back

The Exterior Angle Theorem states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles.

Front

What is the Base Angle Theorem?

Back

The Base Angle Theorem states that in an isosceles triangle, the angles opposite the equal sides are also equal.

Front

If angle A and angle B are the base angles of an isosceles triangle, what can be said about their measures?

Back

Angle A = Angle B.

Front

How do you find the measure of an exterior angle of a triangle?

Back

To find the measure of an exterior angle, add the measures of the two non-adjacent interior angles.

Front

If one interior angle of a triangle is 40° and another is 60°, what is the measure of the exterior angle adjacent to the 60° angle?

Back

The exterior angle is 80° (40° + 60°).

Front

In a triangle, if one angle measures 70°, what is the sum of the measures of the other two angles?

Back

The sum of the other two angles is 110° (180° - 70°).

Front

What is the relationship between the angles in an isosceles triangle?

Back

The angles opposite the equal sides are equal.

Front

If the exterior angle of a triangle is 120°, what are the possible measures of the two non-adjacent interior angles?

Back

The sum of the two non-adjacent interior angles must be 120°.

Front

In triangle ABC, if angle A = 50° and angle B = 60°, what is angle C?

Back

Angle C = 70° (180° - 50° - 60°).

Front

If the base angles of an isosceles triangle are each 45°, what is the measure of the vertex angle?

Back

The vertex angle is 90° (180° - 45° - 45°).