Area and Circumference

Front

What is the formula for Circumference of a circle?

Back

C = 2×π×r, where C is the circumference and r is the radius.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

How do you calculate the circumference of a circle if the diameter is known?

Back

C = π×d, where d is the diameter.

Front

What is the formula for the area of a circle?

Back

A = π×r², where A is the area and r is the radius.

Front

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

Back

C = 2×π×7 ≈ 43.98 cm.

Front

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

Back

r = C/(2×π) ≈ 5 inches.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius: d = 2×r.

Front

How do you convert circumference to radius?

Back

r = C/(2×π).

Front

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

Back

C = 2×π×10 ≈ 62.83 inches.

Front

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

Back

A = π×3² ≈ 28.27 square inches.