When math is in question people are having a lot of troubles and even rejection. The construction in meanwhile is dealing to all shapes that appears in their projects and are calculation all needed values for their purpose. They use a lot of formulas that people learn at school and probably never or very rare use them trough life.
The images bellow are all connected with the construction beams and the formulas used for all that needs. Probably you have forgotten many of them… I have!