Area & Circumference of Circles

Front

What is the definition of a radius in a circle?

Back

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

Front

What is the definition of a diameter in a circle?

Back

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

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 5 cm, what is the circumference?

Back

Circumference = 2 × π × 5 cm ≈ 31.42 cm.

Front

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

Back

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

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the length of the radius.

Front

If a circle has a circumference of 12.56 cm, what is its diameter?

Back

Diameter = Circumference / π ≈ 4 cm.

Front

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

Back

Area = π × (3 m)² ≈ 28.27 m².

Front

What do you need to calculate to find out how much fencing is required for a circular playground?

Back

You need to calculate the circumference of the playground.