Central and Inscribed Angles

Front

What is a central angle?

Back

A central angle is an angle whose vertex is at the center of a circle and whose sides (rays) extend to the circumference.

Front

What is an inscribed angle?

Back

An inscribed angle is an angle formed by two chords in a circle which have a common endpoint. The vertex of the angle is on the circle.

Front

How do you calculate the measure of a central angle?

Back

The measure of a central angle is equal to the measure of the arc it intercepts.

Front

How do you calculate the measure of an inscribed angle?

Back

The measure of an inscribed angle is half the measure of the arc it intercepts.

Front

If the measure of arc AB is 140°, what is the measure of the inscribed angle ACB?

Back

The measure of angle ACB is 70°.

Front

What is the relationship between a central angle and an inscribed angle that intercept the same arc?

Back

The central angle is twice the measure of the inscribed angle.

Front

If m∠ABC = 35°, what is the measure of arc AC?

Back

The measure of arc AC is 70°.

Front

What is the measure of arc JK if m∠JLK = 60°?

Back

The measure of arc JK is 120°.

Front

If the measure of arc AD is 38°, what is the measure of the inscribed angle that intercepts arc AD?

Back

The measure of the inscribed angle is 19°.

Front

What is the formula for finding the measure of an arc?

Back

The measure of an arc is equal to the measure of the central angle that intercepts it.