SLO Area and Circumference of a Circle

Front

What is the formula for the circumference of a circle?

Back

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

Front

What is the formula for the area of a circle?

Back

A = πr², where A is area and r is radius.

Front

If the circumference of a circle is 25.12 inches, what is the diameter?

Back

Diameter = Circumference / π = 25.12 / 3.14 = 8 inches.

Front

What is the distance around a circle called?

Back

Circumference.

Front

What is the radius of a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

If a circle has a radius of 12 inches, what is its circumference?

Back

C = 2πr = 2 × 3.14 × 12 = 75.36 inches.

Front

What is the diameter of a circle if the radius is 5 inches?

Back

Diameter = 2 × radius = 2 × 5 = 10 inches.

Front

How do you find the area of a circle with a diameter of 10 inches?

Back

First, find the radius: r = diameter / 2 = 10 / 2 = 5 inches. Then, A = πr² = 3.14 × 5² = 78.5 square inches.

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × radius.

Front

If the area of a circle is 113.04 cm², what is the radius?

Back

r = √(A/π) = √(113.04/3.14) ≈ 6 inches.