Angle Addition and Angle Bisectors

Front

What is an angle?

Back

An angle is formed by two rays (sides of the angle) that share a common endpoint (the vertex).

Front

What is the vertex of an angle?

Back

The vertex of an angle is the point where the two rays meet.

Front

What is the Angle Addition Postulate?

Back

The Angle Addition Postulate states that if point B is in the interior of angle AOC, then m∠AOB + m∠BOC = m∠AOC.

Front

What is an angle bisector?

Back

An angle bisector is a ray that divides an angle into two equal parts.

Front

How do you find the measure of an angle using its bisector?

Back

If a ray bisects an angle, the measure of each of the two smaller angles is half the measure of the original angle.

Front

If m∠A = 60°, what is m∠B if ray OB is the bisector of ∠A?

Back

m∠B = 30°.

Front

What is the sum of the angles in a triangle?

Back

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

Front

If two angles are complementary, what is the sum of their measures?

Back

The sum of the measures of two complementary angles is 90°.

Front

If two angles are supplementary, what is the sum of their measures?

Back

The sum of the measures of two supplementary angles is 180°.

Front

What is a right angle?

Back

A right angle measures exactly 90°.