Exterior 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.

Tags

CCSS.8.G.A.5

Front

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

Back

The exterior angle is 100° (40° + 60°).

Tags

CCSS.8.G.A.5

Front

What is the relationship between an exterior angle and its adjacent interior angle?

Back

The exterior angle is equal to the sum of the two opposite interior angles, not the adjacent one.

Tags

CCSS.8.G.A.5

Front

How do you find the measure of an unknown angle using the Exterior Angle Theorem?

Back

Add the measures of the two non-adjacent interior angles to find the measure of the exterior angle.

Tags

CCSS.8.G.A.5

Front

If an exterior angle measures 130°, what are the possible measures of the two non-adjacent interior angles?

Back

The sum of the two non-adjacent interior angles must equal 130°.

Tags

CCSS.8.G.A.5

Front

What is the sum of the interior angles of a triangle?

Back

The sum of the interior angles of a triangle is always 180°.

Tags

CCSS.8.G.A.5

Front

If one angle of a triangle is 70° and another is 50°, what is the measure of the exterior angle at the vertex of the 70° angle?

Back

The exterior angle is 60° (50° + 10°).

Tags

CCSS.8.G.A.5

Front

Can the Exterior Angle Theorem be applied to polygons other than triangles?

Back

No, the Exterior Angle Theorem specifically applies to triangles.

Tags

CCSS.8.G.A.5

Front

What is the formula to calculate the measure of an exterior angle?

Back

Exterior Angle = Interior Angle 1 + Interior Angle 2.

Tags

CCSS.8.G.A.5

Front

If the exterior angle is 94°, what are the measures of the two non-adjacent interior angles if one is 40°?

Back

The other angle must be 54° (94° - 40°).

Tags

CCSS.8.G.A.5