Circumference of Circles

Front

What is the formula to calculate the circumference of a circle?

Back

Circumference = π × diameter (C = πd) or Circumference = 2 × π × radius (C = 2πr)

Front

What is the value of π (pi) commonly approximated as?

Back

π is commonly approximated as 3.14.

Front

If a circle has a diameter of 10 feet, what is its circumference?

Back

Circumference = π × diameter = 3.14 × 10 = 31.4 feet.

Front

What is the diameter of a circle if its circumference is 31.4 feet?

Back

Diameter = Circumference / π = 31.4 / 3.14 = 10 feet.

Front

What is the radius of a circle with a diameter of 8 feet?

Back

Radius = Diameter / 2 = 8 / 2 = 4 feet.

Front

How do you convert diameter to radius?

Back

Radius = Diameter / 2.

Front

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

Back

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

Front

If a circular garden has a circumference of 62.8 feet, what is its diameter?

Back

Diameter = Circumference / π = 62.8 / 3.14 = 20 feet.

Front

What is the circumference of a circle with a diameter of 3.5 feet?

Back

Circumference = π × diameter = 3.14 × 3.5 = 10.99 feet.

Front

What is the relationship between diameter and circumference?

Back

The circumference is directly proportional to the diameter; as the diameter increases, the circumference increases.