Circumference & Area of Circles

Front

What is the definition of a circle?

Back

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

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is given by the formula: C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

The area (A) of a circle is given by the formula: A = πr², where r is the radius.

Front

What is the difference between radius and diameter?

Back

The radius is the distance from the center of the circle to any point on its circumference, while the diameter is twice the radius and is the distance across the circle through the center.

Front

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

Back

The diameter is 20 cm, calculated as Diameter = 2 × Radius.

Front

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

Back

The circumference is 31.4 cm, calculated as C = 2π(5) ≈ 31.4 cm.

Front

If the radius of a circle is 7 cm, what is the area?

Back

The area is 153.86 cm², calculated as A = π(7)² ≈ 153.86 cm².

Front

What is the value of π (pi) approximately?

Back

π (pi) is approximately 3.14.

Front

How do you calculate the distance traveled by a point on the circumference after one complete rotation?

Back

The distance traveled is equal to the circumference of the circle.

Front

If a circle has a circumference of 62.8 cm, what is its radius?

Back

The radius is 10 cm, calculated as r = C/(2π) = 62.8/(2π) ≈ 10 cm.