Circle Basics, Central Angles, and Arcs.

Front

What is a circle?

Back

A circle is a set of points in a plane that are equidistant from a fixed point called the center.

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 an arc in a circle?

Back

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

Front

How do you measure an arc?

Back

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

Front

What is a major arc?

Back

A major arc is an arc that measures more than 180 degrees.

Front

What is a minor arc?

Back

A minor arc is an arc that measures less than 180 degrees.

Front

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

Back

The measure of the arc is equal to the measure of the central angle in degrees.

Front

How do you find the measure of an arc if given the central angle?

Back

The measure of the arc is the same as the measure of the central angle.

Front

What is the formula for the circumference of a circle?

Back

The circumference C of a circle is given by the formula C = 2πr, where r is the radius.

Front

If the radius of a circle is 10 cm, what is the circumference?

Back

C = 2π(10) = 20π cm.