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

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 12 cm, what is the radius?

Back

Radius = diameter ÷ 2 = 12 cm ÷ 2 = 6 cm.

Front

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

Back

Circumference = 2 × π × 7 cm ≈ 43.98 cm.

Front

True or False: A circle can have more than one radius.

Back

False. A circle has an infinite number of radii, but they all measure the same length.

Front

What is the relationship between diameter and radius?

Back

The diameter is always twice the length of the radius.

Front

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

Back

Radius = Circumference ÷ (2 × π) ≈ 5 cm.

Front

What is the circumference of a circle with a diameter of 10 inches?

Back

Circumference = π × diameter = π × 10 inches ≈ 31.4 inches.