Circumference of Circles

Front

What is the definition of the radius of a circle?

Back

The radius of a circle is the distance from the center of the circle to any point on its circumference.

Front

What is the definition of the diameter of a circle?

Back

The diameter of a circle is the distance across the circle through its center, equal to twice the radius.

Front

What is the formula for finding the circumference of a circle using the diameter?

Back

C = π·d, where C is the circumference and d is the diameter.

Front

What is the formula for finding the circumference of a circle using the radius?

Back

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

Front

If the radius of a circle is 10 cm, what is the circumference?

Back

C = 2·π·10 cm ≈ 62.83 cm.

Front

If the diameter of a circle is 20 cm, what is the radius?

Back

The radius is 10 cm, since the radius is half of the diameter.

Front

What is π (pi) in relation to circles?

Back

π (pi) is a mathematical constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

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

Back

Use the formula C = 2·π·r.

Front

What is the relationship between diameter and radius?

Back

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

Front

If a circle has a circumference of 31.4 cm, what is its diameter?

Back

The diameter is 10 cm, since C = π·d, thus d = C/π.