Circles

Front

What is a circle?

Back

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

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 area of a circle?

Back

Area = π × radius².

Front

If the radius of a circle is 9.5 mm, what is the diameter?

Back

Diameter = 2 × radius = 2 × 9.5 mm = 19 mm.

Front

If the radius of a circle is 13.5 mm, what is the circumference?

Back

Circumference = 2 × π × 13.5 mm ≈ 84.78 mm.

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 formula for the area of a circle?

Back

Area = π × radius².

Front

What is the relationship between radius and diameter?

Back

The diameter is always twice the radius.