Circumference and Area of Circles

Front

What is the formula for calculating the circumference of a circle?

Back

Circumference = π × diameter or Circumference = 2 × π × radius.

Front

What is the value of π (pi) to two decimal places?

Back

3.14

Front

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

Back

Radius = diameter / 2 = 10 cm / 2 = 5 cm.

Front

Calculate the circumference of a circle with a radius of 7 cm. Express your answer to two decimal places.

Back

Circumference = 2 × π × 7 cm = 43.98 cm.

Front

What is the formula for calculating the area of a circle?

Back

Area = π × radius².

Front

Calculate the area of a circle with a radius of 4 cm. Express your answer to two decimal places.

Back

Area = π × (4 cm)² = 50.27 cm².

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × radius.

Front

If a circle has an area of 78.54 cm², what is its radius?

Back

Radius = √(Area / π) = √(78.54 cm² / 3.14) = 5 cm.

Front

A circular garden has a radius of 3 m. What is its circumference?

Back

Circumference = 2 × π × 3 m = 18.85 m.

Front

A circular pizza has a diameter of 12 inches. What is its area?

Back

Area = π × (6 inches)² = 113.10 in².