Math 7: 8-2: Circumference of a Circle

Front

What is the formula for the circumference of a circle?

Back

C = πd or C = 2πr, where C is circumference, d is diameter, and r is radius.

Front

If a circle has a diameter of 10 cm, what is its radius?

Back

5 cm (Radius is half of the diameter).

Front

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

Back

C = 2π(7) = 14π cm or approximately 43.98 cm.

Front

What is the relationship between diameter and radius?

Back

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

Front

If the circumference of a circle is 31.40 cm, what is its diameter?

Back

d = C/π = 31.40/π ≈ 10 cm.

Front

What is π (pi)?

Back

π is a mathematical constant approximately equal to 3.14, representing the ratio of a circle's circumference to its diameter.

Front

How do you convert diameter to radius?

Back

Divide the diameter by 2.

Front

What is the circumference of a circle with a diameter of 20 inches?

Back

C = πd = π(20) ≈ 62.83 inches.

Front

If a bicycle tire has a radius of 13.5 inches, what is its diameter?

Back

27 inches (Diameter is twice the radius).

Front

What is the circumference of a circle with a radius of 10 m?

Back

C = 2π(10) = 20π m or approximately 62.83 m.