Circumference and Area of a Circle

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 diameter of 10 cm, what is its radius?

Back

5 cm (Radius is half of the diameter).

Front

What does 'diameter' mean in relation to a circle?

Back

The diameter is the distance across the circle through its center, equal to twice the radius.

Front

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

Back

C = 2π(7) = 14π ≈ 43.98 cm.

Front

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

Back

A = π(3)² = 9π ≈ 28.27 cm².

Front

What does 'radius' mean in relation to a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

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

Back

5 cm (C = 2πr, so r = C/(2π)).

Front

What is the relationship between diameter and radius?

Back

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

Front

What is the circumference of a circle with a diameter of 12 m?

Back

C = π(12) ≈ 37.68 m.