I recently read somewhere that , but I cannot seem to find this identity anywhere on the internet. Does anyone know what this is called, or where I can find the same identities (with x's and y's) for the other trig functions?
Take a look at where that equation comes from . . .
Code:| | * | * | | h * | | * | y | * | | * @ | - - * - - - - - + - - | x
We have angle in a right triangle.
The adjacent side is ; the opposite side is
Using Pythagorus, we find that: .
Therefore, we have: