Circumference of a Circle

Front

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

Back

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

Front

If the diameter of a circle is 9 ft, what is the circumference rounded to the nearest tenth?

Back

28.3 ft.

Front

If the diameter of a circle is 12 in, what is the circumference rounded to the nearest tenth?

Back

37.7 in.

Front

If the radius of a circle is 13 ft, what is the circumference rounded to the nearest tenth?

Back

81.6 ft.

Front

If the radius of a circle is 8 m, what is the circumference rounded to the nearest tenth?

Back

50.2 m.

Front

What is the value of π (pi) approximately?

Back

3.14.

Front

How do you convert radius to diameter?

Back

Diameter = 2 × radius.

Front

How do you convert diameter to radius?

Back

Radius = diameter ÷ 2.

Front

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

Back

31.4 mi.

Front

What is the relationship between diameter and circumference?

Back

The circumference is directly proportional to the diameter.