Parts of a Circle

Front

What is a circle?

Back

A circle is the set of all points equidistant from a common point called the center.

Front

What is the diameter of a circle?

Back

The diameter is a line segment that passes through the center of the circle and has its endpoints on the circle. It is twice the length of the radius.

Front

What is the radius of a circle?

Back

The radius is the line segment from the center of the circle to any point on the circle.

Front

What is a chord in a circle?

Back

A chord is a line segment whose endpoints lie on the circle.

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle.

Front

If the radius of a circle is 5 units, what is the diameter?

Back

The diameter is 10 units (diameter = 2 x radius).

Front

If the diameter of a circle is 14 units, what is the radius?

Back

The radius is 7 units (radius = diameter / 2).

Front

What is the relationship between radius and diameter?

Back

The diameter is always twice the length of the radius.

Front

Identify the radii in a circle with center O and points A, B, and C on the circle.

Back

OA, OB, and OC are all radii of the circle.

Front

What is the formula for the circumference of a circle?

Back

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