Circumference, Arc Measure, and Arc Length

Front

What is the formula for the circumference of a circle?

Back

C = πd or C = 2πr, where d is the diameter and r is the radius.

Front

If the radius of a circle is 7 in, what is the circumference?

Back

C = 2π(7) = 14π in.

Front

How many degrees are in a semicircle?

Back

180 degrees.

Front

What is a minor arc?

Back

An arc that is smaller than a semicircle.

Front

What is a major arc?

Back

An arc that is larger than a semicircle.

Front

What is the measure of a full circle in degrees?

Back

360 degrees.

Front

If an arc measures 120 degrees, what fraction of the circle does it represent?

Back

120/360 = 1/3 of the circle.

Front

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

Back

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

Front

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

Back

Radius = diameter/2 = 10/2 = 5 cm.

Front

What is the length of an arc if the radius is 4 cm and the central angle is 90 degrees?

Back

Arc length = (θ/360) * 2πr = (90/360) * 2π(4) = 2π cm.