Home > Algebra > Formulas for Problem Solving

What is the formula for the area of a circle?

Answer 1

Savannah Anderson

#A=pi*r^2=# area of a circle

By signing up, you agree to our Terms of Service and Privacy Policy

Answer 2

Kennedy Adams

The formula #A = pi r^2# expresses the area of a circle in terms of its radius.

The number #pi# is defined as the ratio of the circumference of a circle to its diameter (i.e. to twice its radius), hence the formula #2 pi r#.

The area of a circle is given by the formula:

#A = pi r^2#

To see why, you can divide a circle into a number of equal segments and stack them head to tail to form a sort of parallelogram with 'bumpy' sides. The long sides will be about half the circumference in length - that is #pi r#, while the height of the parallelogram will be about #r#. So the area is seen to be about #pi r^2#.

This approximation gets better the more segments you have, but here's an animated illustration I put together with just #8# segments...

By signing up, you agree to our Terms of Service and Privacy Policy

Answer 3

Eva Abramson

The formula for the area of a circle is A = πr^2, where A represents the area and r represents the radius of the circle.

By signing up, you agree to our Terms of Service and Privacy Policy

Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.