Sine, Cosine and Tangent are all based on a Right-Angled Triangle
There are 4 quadrants in a central circle
The angle lies in the third quadrant based on the number of degrees of the central circle which means the answer will be negative
This is for degrees not radians
If using your calculator make sure the calculator is set for degrees and not radians (it should say DEG at the top)
Input 235
push "COS)
and you will get -.57
=-sin((7 pi)/36)
=-0.57
