Circle Unit Vocabulary

Front

What is a central angle?

Back

An angle whose vertex is at the center of the circle and whose sides intersect the circle.

Front

What is an inscribed angle?

Back

An angle formed by two chords in a circle which have a common endpoint.

Front

Define a minor arc.

Back

An arc of a circle that is less than 180 degrees.

Front

Define a major arc.

Back

An arc of a circle that is greater than 180 degrees.

Front

What is a semicircle?

Back

An arc of a circle that is exactly 180 degrees.

Front

What is the relationship between an inscribed angle and the arc it intercepts?

Back

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

Front

What is the relationship between a central angle and the arc it intercepts?

Back

The central angle is equal to the measure of the intercepted arc.

Front

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

Back

Arc length = (θ/360) * 2πr, where θ is the central angle in degrees and r is the radius.

Front

What is the formula for finding the area of a sector?

Back

Area of sector = (θ/360) * πr², where θ is the central angle in degrees and r is the radius.

Front

What is the diameter of a circle?

Back

The distance across the circle through the center, equal to twice the radius.