Circumference Review

Front

What is the circumference of a circle?

Back

The distance around a circle.

Front

What is the formula to calculate the circumference of a circle?

Back

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

Front

If the radius of a circle is 7 cm, what is its circumference?

Back

C = 2π(7) ≈ 43.98 cm.

Front

What is the diameter of a circle with a radius of 5 cm?

Back

The diameter is 10 cm (d = 2r).

Front

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

Back

r = C/(2π) ≈ 5 cm.

Front

What is the relationship between diameter and circumference?

Back

The circumference is π times the diameter (C = πd).

Front

If a circle has a circumference of 78.5 cm, what is its diameter?

Back

d = C/π ≈ 25 cm.

Front

What is the circumference of a circle with a diameter of 20 cm?

Back

C = π(20) ≈ 62.83 cm.

Front

How does changing the radius affect the circumference of a circle?

Back

Increasing the radius increases the circumference; they are directly proportional.

Front

What is the circumference of a circle with a radius of 10 inches?

Back

C = 2π(10) ≈ 62.83 inches.