Area and Circumference of Circles

Front

What is the formula for the circumference of a circle?

Back

C = 2πr or C = πd, where r is the radius and d is the diameter.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

If a circle has a radius of 7 cm, what is its circumference in terms of pi?

Back

14π cm.

Front

If a circle has a diameter of 10 inches, what is its radius?

Back

5 inches.

Front

What is the value of π (pi) approximately?

Back

3.14.

Front

If the radius of a circle is doubled, how does the area change?

Back

The area increases by a factor of four.

Front

What is the relationship between diameter and radius?

Back

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

Front

If a circle has a circumference of 12π, what is its radius?

Back

6 units.

Front

What is the circumference of a circle with a radius of 3 m?

Back

6π m.

Front

If the area of a circle is 50π cm², what is its radius?

Back

5√2 cm.