What is the formula for the area of a circle?
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
This approximation gets better the more segments you have, but here's an animated illustration I put together with just