Exterior Angles of a Triangle

Front

What is an exterior angle of a triangle?

Back

An exterior angle of a triangle is formed by one side of the triangle and the extension of an adjacent side. It is equal to the sum of the two opposite interior angles.

Front

State 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

If angle A = 40° and angle B = 60°, what is the measure of the exterior angle at vertex C?

Back

The exterior angle at vertex C is 100°, calculated as 40° + 60°.

Front

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

Back

An exterior angle and its adjacent interior angle are supplementary, meaning they add up to 180°.

Front

How do you find the measure of an unknown angle in a triangle if you know the other two angles?

Back

To find the unknown angle, subtract the sum of the known angles from 180°. For example, if angle A = 50° and angle B = 70°, then angle C = 180° - (50° + 70°) = 60°.

Front

What is the sum of the exterior angles of any polygon?

Back

The sum of the exterior angles of any polygon is always 360°, regardless of the number of sides.

Front

If angle D is an exterior angle and measures 120°, what are the measures of the two opposite interior angles?

Back

The two opposite interior angles must sum to 120°. For example, if one angle is 70°, the other must be 50°.

Front

What is the measure of an exterior angle if the two opposite interior angles are 45° and 55°?

Back

The measure of the exterior angle is 100°, calculated as 45° + 55°.

Front

Can an exterior angle be greater than 180°?

Back

No, an exterior angle cannot be greater than 180° because it is formed by extending a side of the triangle.

Front

If angle E is 30° and angle F is 50°, what is the measure of the exterior angle at vertex G?

Back

The exterior angle at vertex G is 80°, calculated as 30° + 50°.