Circumference of Circles

Front

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

Back

C = π·d or C = 2·π·r, where C is the circumference, d is the diameter, and r is the radius.

Front

If the radius of a circle is 5 inches, what is its circumference using π ≈ 3.14?

Back

31.4 inches.

Front

What does the symbol 'C' represent in the formula C = π·d?

Back

C represents the circumference of the circle.

Front

How do you calculate the circumference of a circle if you know the diameter?

Back

Use the formula C = π·d, where d is the diameter.

Front

What is the approximate circumference of a circle with a diameter of 50 mm using π ≈ 3.14?

Back

157 mm.

Front

If a circle has a circumference of 62.8 feet, what is its radius?

Back

The radius is 10 feet (using C = 2·π·r).

Front

What is the relationship between the radius and diameter of a circle?

Back

The diameter is twice the radius (d = 2·r).

Front

How can you express the circumference of a circle in terms of its radius?

Back

C = 2·π·r.

Front

What is the circumference of a circle with a radius of 6 cm using π ≈ 3.14?

Back

37.68 cm.

Front

What is the value of π (pi) used for approximate calculations?

Back

π is approximately 3.14.