Circles - Circumference and Area

Front

What is the formula for the circumference of a circle?

Back

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

Front

What is the formula for the area of a circle?

Back

Area = π × radius².

Front

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

Back

Circumference = 2π × 5 cm = 10π or about 31.4 cm.

Front

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

Back

Area = π × (5 cm)² = 25π or about 78.5 cm².

Front

What does π (pi) represent in relation to circles?

Back

π is the ratio of the circumference of any circle to its diameter.

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × radius.

Front

How do you convert diameter to radius?

Back

Radius = diameter ÷ 2.

Front

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

Back

Diameter = 2 × 7 cm = 14 cm.

Front

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

Back

Circumference = π × 12 feet = 12π or about 37.68 feet.

Front

What is the area of a circle with a diameter of 10 centimeters?

Back

Area = 25π or about 78.5 cm².