Circles

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 circumference of a circle?

Back

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

Front

What is the formula for the area of a circle?

Back

Area = π × radius².

Front

If the radius of a circle is 18, what is the diameter?

Back

Diameter = 2 × radius = 36.

Front

If the diameter of a circle is 48, what is the radius?

Back

Radius = Diameter ÷ 2 = 24.

Front

What is π (pi)?

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

What is the relationship between radius and diameter?

Back

The diameter is always twice the length of the radius.

Front

How can you find the circumference if you know the area of a circle?

Back

First, find the radius using Area = π × radius², then use Circumference = 2 × π × radius.

Front

What is the circumference of a circle with a radius of 14?

Back

Circumference = 2 × π × 14 ≈ 87.96.