Radius, Diameter, and Circumference

Front

What is the definition of a radius?

Back

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

Front

What is the definition of a diameter?

Back

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

Front

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

Back

The circumference (C) can be calculated using the formula C = πd or C = 2πr.

Front

If the radius of a circle is 3 cm, what is the diameter?

Back

The diameter is 6 cm (diameter = 2 × radius).

Front

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

Back

The radius is 5 cm (radius = diameter / 2).

Front

What is the approximate value of π (pi)?

Back

π (pi) is approximately 3.14.

Front

How do you find the circumference of a circle with a radius of 4 cm?

Back

C = 2πr = 2 × 3.14 × 4 = 25.12 cm.

Front

True or False: The circumference of a circle is the same as its area.

Back

False.

Front

What is the relationship between diameter and circumference?

Back

The circumference is directly proportional to the diameter; C = πd.

Front

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

Back

The diameter is 10 cm (d = C/π).