Circumference and Area of a Circle

Front

What is the diameter of a circle?

Back

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

Front

What is the radius of a circle?

Back

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

Front

What does 'circumference' mean?

Back

Circumference is the distance around a circle.

Front

How do you calculate the circumference of a circle?

Back

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

Front

What is the formula for the area of a circle?

Back

Area = π × radius².

Front

If the radius of a circle is 3 cm, what is its area?

Back

Area = π × (3 cm)² = 28.26 cm² (using π ≈ 3.14).

Front

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

Back

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

Front

What is the area of a circle with a radius of 5 inches?

Back

Area = π × (5 inches)² = 78.5 inches² (using π ≈ 3.14).

Front

What is the circumference of a circle with a radius of 4 m?

Back

Circumference = 2 × π × 4 m = 25.12 m (using π ≈ 3.14).

Front

If a circle has an area of 50 cm², what is its radius?

Back

Radius = √(Area / π) = √(50 cm² / 3.14) ≈ 3.99 cm.