Radius, Diameter, Circumference

Front

What is the definition of radius?

Back

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

Front

What is the definition of diameter?

Back

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

Front

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

Back

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

Front

If the radius of a circle is 5 cm, what is the diameter?

Back

Diameter = 2 × radius = 2 × 5 cm = 10 cm.

Front

If the diameter of a circle is 20 cm, what is the radius?

Back

Radius = diameter ÷ 2 = 20 cm ÷ 2 = 10 cm.

Front

What is the approximate value of π (pi)?

Back

π (pi) is approximately 3.14.

Front

How do you find the circumference if you know the radius?

Back

Circumference = 2 × π × radius.

Front

What is the circumference of a circle with a diameter of 8 cm?

Back

Circumference = π × diameter = 3.14 × 8 cm = 25.12 cm.

Front

If the circumference of a circle is 31.4 cm, what is the diameter?

Back

Diameter = Circumference ÷ π = 31.4 cm ÷ 3.14 = 10 cm.

Front

What is the relationship between diameter and radius?

Back

The diameter is always twice the length of the radius.