Circumference and Area

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

How do you calculate 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 7 meters, what is the circumference?

Back

C = 2π(7) = 14π meters or approximately 43.96 meters.

Front

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

Back

A = π(5)² = 25π square inches or approximately 78.54 square inches.

Front

What is the value of π (pi) used in calculations?

Back

π is approximately 3.14.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius (D = 2r).

Front

How do you convert diameter to radius?

Back

Radius is half of the diameter (r = D/2).

Front

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

Back

C = πD = π(10) = 10π cm or approximately 31.42 cm.

Front

What is the area of a circle with a radius of 3 yards?

Back

A = π(3)² = 9π square yards or approximately 28.27 square yards.

Front

If a circle has a circumference of 31.4 meters, what is its radius?

Back

r = C/(2π) = 31.4/(2π) = 5 meters.