## Basic Geometry

The *perimeter* of any polygon is calculated by finding the sum of the lengths of its sides.

$P = A + B + C + D + E$

The *area* of a region is defined as its amount of surface. The area for a rectangle is calculated by multiplying its sides:

$A = l \times h$

If the units of $l$ and $h$ are $cm$, the unit of $A$ will be $cm^2$. In case of a square the *area* is simply the length of one of its sides *squared* ($A = l^2$)

The distance of a circle is found by the formula $C = 2\pi r$, where $r$ is the *radius* - the line from the center of the circle straight to its edge.

$\pi = 3.14159$ (approximately)

## Pythagorean Theorem

Given the lengths of 2 sides of a right angular triangle (a triangle of which one angle is 90 degrees), the length of the third size can be calculated. Given the formula $b^2 + h^2 = c^2$ which assumes $b$ and $h$ to be the sides adjacent to the right angle and $c$ to be the side opposite to the angle, one may find an unknown side length by solving the resulting equation.