Radius, Diameter, and Circumference of circles

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 edge.

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle, passing through the center. It is 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 value of π (pi)?

Back

π (pi) is approximately 3.14 or 22/7.

Front

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

Back

The diameter is 20 feet (diameter = 2 × radius).

Front

If the diameter of a circle is 14 cm, what is the circumference?

Back

Circumference = π × diameter = 3.14 × 14 cm = 43.96 cm.

Front

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

Back

Circumference = 2 × π × radius = 2 × 3.14 × 5 = 31.4 inches.

Front

What does the term 'circumference' refer to?

Back

Circumference is the measurement around the circle.

Front

If a circle has a circumference of 31.4 cm, what is its radius?

Back

Radius = Circumference / (2 × π) = 31.4 / (2 × 3.14) = 5 cm.

Front

What is the relationship between diameter and radius?

Back

The diameter is always twice the radius.