Triangle Exterior Angle Theorem

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What is the Triangle Exterior Angle Theorem?

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The Triangle 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 remote interior angles.

Tags

CCSS.8.G.A.5

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What are remote interior angles?

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Remote interior angles are the two angles inside a triangle that are not adjacent to a given exterior angle.

Tags

CCSS.8.G.A.5

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If one exterior angle measures 120°, what is the sum of the remote interior angles?

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The sum of the remote interior angles is 120°.

Tags

CCSS.8.G.A.5

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If Angle W is an exterior angle, which angles are the remote interior angles?

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The remote interior angles are the two angles inside the triangle that are not adjacent to Angle W.

Tags

CCSS.8.G.A.5

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

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The exterior angle is equal to the sum of the two remote interior angles, while the adjacent interior angle is not included in this sum.

Tags

CCSS.8.G.A.5

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If Angle A = 30° and Angle B = 50°, what is the measure of the exterior angle at Angle C?

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The exterior angle at Angle C is 80° (30° + 50°).

Tags

CCSS.8.G.A.5

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

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To find an unknown angle, add the measures of the two remote interior angles.

Tags

CCSS.8.G.A.5

Front

What is the sum of the angles in a triangle?

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

Tags

CCSS.8.G.A.5

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If Angle X = 70° and Angle Y = 40°, what is the measure of the exterior angle adjacent to Angle Z?

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The exterior angle adjacent to Angle Z is 110° (70° + 40°).

Tags

CCSS.8.G.A.5

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

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The measure of an exterior angle = Measure of remote interior angle 1 + Measure of remote interior angle 2.

Tags

CCSS.8.G.A.5