Circumference and Area of Circles

Front

What is the formula for the area of a circle?

Back

Area = π × r², where r is the radius.

Front

What is the formula for the circumference of a circle?

Back

Circumference = 2 × π × r, where r is the radius.

Front

If a circle has a radius of 5 cm, what is its area?

Back

Area = π × (5 cm)² = 78.54 cm² (approximately).

Front

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

Back

Radius = Diameter / 2 = 10 m / 2 = 5 m.

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × Radius.

Front

How do you convert diameter to radius?

Back

Divide the diameter by 2.

Front

What is the area of a circle with a radius of 7 inches?

Back

Area = π × (7 in)² = 153.94 in² (approximately).

Front

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

Back

Circumference = 2 × π × 3 ft = 18.85 ft (approximately).

Front

If the area of a circle is 50.27 cm², what is the radius?

Back

Radius = √(Area / π) = √(50.27 / π) ≈ 4 cm.

Front

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

Back

Area = π × (6 m)² = 113.1 m² (approximately).