Dont know how to calculate angles in a triangle or not sure how to use Sine, Cosine etc. 

A simple angle calculator for Right-angled triangles. Calculate unknown angles or lengths by entering ANY TWO (2) known variables into the text boxes. To enter a value, click inside one of the text boxes. Click on the "Calculate" button to solve for all unknown variables.

A handy tool for calculating roof lengths, cutting angles, stair angles