Circles

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where C is the circumference and r is the radius.

Front

What is the formula for the area of a circle?

Back

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

Front

If the radius of a circle is 5 inches, what is the circumference?

Back

31.4 inches.

Front

If the radius of a circle is 5 inches, what is the area?

Back

78.5 square inches.

Front

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

Back

10 inches.

Front

What is the relationship between diameter and radius?

Back

Diameter is twice the radius (D = 2r).

Front

What is π (pi)?

Back

A mathematical constant approximately equal to 3.14, representing the ratio of a circle's circumference to its diameter.

Front

How do you calculate the area of a circle with a radius of 5 ft?

Back

A = π(5)(5) = 78.5 square feet.

Front

What is the circumference of a circle with a diameter of 10 inches?

Back

31.4 inches.

Front

If a circle has a radius of 7 cm, what is its area?

Back

A = π(7)(7) ≈ 153.86 square cm.