Circumference and Area of a Circle

The radius of a circle is 13 in. Find its area in terms of π.

169π

The radius of a circle is 14 ft. Find its area in terms of π.

196π

The radius of a circle is 10 in. Find its circumference in terms of π.

20π

The radius of a circle is 12 in. Find its circumference in terms of π.

24π

The radius of a circle is 12.5. What is the diameter?

25

The radius of a circle is 6 ft. Find its area in terms of π.

36π

The radius of a circle is 19 ft. Find its circumference in terms of π.

38π

The diameter of a circle is 40 ft. Find its circumference in terms of π.

40π

The diameter of a circle is 4 ft. Find its area in terms of π.

4π

The diameter of a circle is 10. What is the radius?

5

The diameter of a circle is 18 cm. Find its area in terms of π.

81π

The diameter of a circle is 8 ft. Find its circumference in terms of π.

8π

Formula to find area of a circle

Area = PI times radius squared

Formula to find circumference

C=2πr

Circumference

Distance AROUND the circle

You are given the diameter. How can you find the radius?

Divide diameter by two

Diameter

Line segment that passes through the center with endpoints on the circle

You are given the radius. How can you find the diameter?

Multiply radius by 2

Area of a circle

The number of square units INSIDE the circle

Radius

line segment from center of circle to any point on its edge