Area and circumference

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 a circle has a radius of 5 cm, what is its circumference?

Back

C = 2π(5) = 10π or about 31.4 cm.

Front

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

Back

A = π(7)² = 49π or about 153.94 mm².

Front

What is the relationship between diameter and radius?

Back

Diameter (d) = 2 × Radius (r).

Front

If a circle has a diameter of 20 cm, what is its radius?

Back

Radius (r) = Diameter (d) / 2 = 20 cm / 2 = 10 cm.

Front

What is the circumference of a circle with a radius of 12.5 mm?

Back

C = 2π(12.5) = 25π or about 78.5 mm.

Front

What is the area of a circle with a radius of 6 inches?

Back

A = π(6)² = 36π or about 113.1 in².

Front

How do you convert diameter to circumference?

Back

C = π × Diameter (d).

Front

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

Back

C = π(10) = 10π or about 31.4 cm.