Area and Circumference of Circles Practice

Front

What is the formula for the area of a circle?

Back

The formula for the area of a circle is A = πr², where r is the radius.

Front

What is the formula for the circumference of a circle?

Back

The formula for the circumference of a circle is C = 2πr, where r is the radius.

Front

What is the relationship between diameter and radius?

Back

The diameter of a circle is twice the radius (d = 2r).

Front

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

Back

The area is A = π(5)² = 25π cm².

Front

If the diameter of a circle is 10 cm, what is its circumference?

Back

The circumference is C = πd = π(10) = 10π cm.

Front

How do you convert diameter to radius?

Back

To convert diameter to radius, divide the diameter by 2 (r = d/2).

Front

What is the circumference of a circle with a radius of 7 inches?

Back

The circumference is C = 2π(7) = 14π inches.

Front

What is the area of a circle with a diameter of 12 inches?

Back

First, find the radius: r = 12/2 = 6 inches. Then, A = π(6)² = 36π square inches.

Front

What is the value of π (pi) approximately?

Back

The value of π is approximately 3.14.

Front

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

Back

Using the formula C = 2πr, we can find r: r = C/(2π) = 31.4/(2π) = 5 cm.