Exterior Angles

Learn and apply exterior angles.

Lesson 2 of 53 parts Practice Flashcards

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Exterior Angle Theorem

Objective: Apply exterior angle theorem in triangle problems.

An exterior angle equals the sum of two remote interior angles.

Worked examples

Try itA triangle’s two remote interior angles are 21° and 31°. Find the exterior angle.Show answer

52°. Add the remote interior angles.

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Objective: Apply exterior angle theorem in triangle problems.

An exterior angle equals the sum of two remote interior angles.

Worked examples

Try itA triangle’s two remote interior angles are 21° and 31°. Find the exterior angle.Show answer

52°. Add the remote interior angles.

Objective: Apply remote interior angles in triangle problems.

Remote interior angles are the two triangle angles not adjacent to the chosen exterior angle.

Worked examples

Try itAn exterior angle is 81°; one remote interior angle is 31°. Find the other remote interior angle.Show answer

50°. Exterior = sum of remote interior angles, so subtract.

Objective: Apply exterior and adjacent angles in triangle problems.

An exterior angle and its adjacent interior angle form a linear pair totaling 180°.

Worked examples

Try itAn interior angle adjacent to an exterior angle is 41°. Find the exterior angle.Show answer

139°. The adjacent pair sums to 180°.

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