Circles - Area and Circumference

Front

What is a circle?

Back

A circle is a shape consisting of all points in a plane that are a fixed distance (radius) from a center point.

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 the 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 5 inches, what is the area?

Back

Area = π × (5)² = 78.54 square inches.

Front

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

Back

Circumference = 2 × π × 10 = 62.83 inches.

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 twice the length of the radius (Diameter = 2 × Radius).

Front

If a circle has a diameter of 12 inches, what is the radius?

Back

Radius = Diameter / 2 = 12 / 2 = 6 inches.