Pythagoras' theorem

Pythagoras' theorem is used to find the length of a side in a right angle triangle.

c² = a² + b²

, where c is the longest side of the triangle.
For example,

to find c, you will need to do:

c=sqrt(a² + b²).

Example:
1) a = 15, b = 16. Find c.

c = sqrt (15² + 16² ) = sqrt (225 + 256) = sqrt (481) = 21.9317122

2) a = 5, b = 3. Find c.

c = sqrt (5² + 3²) = sqrt (25 + 9) = sqrt (36) = 6

Finding the other side is made very simple by rearranging the equation.
If you are given a long side c and short side b, then you need to find a:

a² = c² - b²;
a = sqrt (c² - b²)

Example:
1) c = 6, b = 3;

a = sqrt (6² - 3³) = sqrt (36 - 9) = sqrt (25) = 5;
a = 5

This is all you'll need to know.
he most important things are the formula and that a triangle must have a right angle.
Next step - trigonometry!