Area and Circumference of a Circle

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

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

Back

C = 2π(5) = 31.42 meters.

Front

What is the relationship between diameter and radius?

Back

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

Front

How do you calculate the diameter if you know the circumference?

Back

D = C/π.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

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

Back

The radius is 5 cm (r = D/2).

Front

What is the circumference of a circle with a diameter of 8 inches?

Back

C = πD = π(8) ≈ 25.13 inches.

Front

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

Back

A = πr² = π(3)² ≈ 28.27 square meters.

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 doubled, how does the circumference change?

Back

The circumference also doubles.