Circles & Circumference

Front

What is the definition of a circle?

Back

A circle is a shape consisting of all points in a plane that are a given distance from a fixed point, called the center.

Front

What is the formula for the circumference of a circle?

Back

C = π * d (where d is the diameter) or C = 2 * π * r (where r is the radius).

Front

What is the relationship between diameter and radius?

Back

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

Front

What does it mean for a shape to be inscribed in a circle?

Back

A shape is inscribed in a circle if all its vertices lie on the circle.

Front

What does it mean for a shape to be circumscribed about a circle?

Back

A shape is circumscribed about a circle if the circle touches all sides of the shape.

Front

How do you calculate the circumference of a circle with a diameter of 3.5 feet?

Back

C = π * d = π * 3.5 ≈ 11.0 feet.

Front

What is the distance around a circle called?

Back

The distance around a circle is called the circumference.

Front

If the radius of a circle is 5 cm, what is the circumference?

Back

C = 2 * π * r = 2 * π * 5 ≈ 31.4 cm.

Front

What is the area of a circle?

Back

The area of a circle is given by the formula A = π * r².

Front

What is the diameter of a circle?

Back

The diameter is the longest distance across the circle, passing through the center.