Circles: Circumference and Area

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 center of a circle?

Back

The center of a circle is the fixed point from which all points on the circle are equidistant.

Front

What is a radius?

Back

A radius is a line segment from the center of the circle to any point on the circle.

Front

What is a diameter?

Back

A diameter is a line segment that passes through the center of the circle and has its endpoints on the circle. It is twice the length of the radius.

Front

How do you calculate the circumference of a circle?

Back

Circumference (C) = 2 × π × r, where r is the radius.

Front

What is the formula for the area of a circle?

Back

Area (A) = π × r², where r is the radius.

Front

If the radius of a circle is 7, what is the diameter?

Back

Diameter = 2 × radius = 2 × 7 = 14.

Front

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

Back

Radius = Diameter / 2 = 10 / 2 = 5.

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.