7.3.a: Radius, Diameter, Circumference

Front

What is the radius of a circle?

Back

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

Front

What is the diameter of a circle?

Back

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

Front

How do you calculate the radius from the diameter?

Back

Divide the diameter by 2.

Front

How do you calculate the diameter from the radius?

Back

Multiply the radius by 2.

Front

What is the formula for the circumference of a circle?

Back

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

Front

What is the value of pi (π)?

Back

Pi (π) is approximately 3.14.

Front

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

Back

5 cm.

Front

If the radius of a circle is 4 m, what is the diameter?

Back

8 m.

Front

What is the relationship between circumference and diameter?

Back

The circumference divided by the diameter equals pi (π).

Front

What is the circumference of a circle with a radius of 3 inches?

Back

Circumference = 2 × π × 3 = 6π inches (approximately 18.84 inches).