Arcs and Angles in Circles

Front

What is an arc in a circle?

Back

An arc is a portion of the circumference of a circle.

Front

Define a central angle.

Back

A central angle is an angle whose vertex is at the center of the circle and whose sides are radii that intersect the circle.

Front

What is the relationship between the central angle and the arc it subtends?

Back

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

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.

Front

How is the measure of an inscribed angle related to the arc it intercepts?

Back

The measure of an inscribed angle is half the measure of the intercepted arc.

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where r is the radius of the circle.

Front

How do you find the measure of a minor arc?

Back

The measure of a minor arc is equal to the measure of the central angle that subtends it.

Front

What is a major arc?

Back

A major arc is an arc that is larger than a semicircle and is measured by subtracting the measure of the minor arc from 360°.

Front

Define a semicircle.

Back

A semicircle is an arc that represents half of a circle, measuring 180°.

Front

What is the relationship between the angles formed by two intersecting chords?

Back

The measure of the angle formed by two intersecting chords is equal to half the sum of the measures of the arcs intercepted by the angle and its vertical angle.