Stair riser height

Calculates stair slope angle from riser height and tread depth.

Helper calculation of stair geometry value 2h + s; it is not a code check or code-based design.

Calculates roof pitch angle as arctangent of rise divided by run.

Calculates sloped roof area from plan area and roof angle plus required material area with waste.

Converts roof plan area into approximate sloped roof area using the pitch angle.

Helper calculation of geometric rafter length from run and rise; it is not code-based design.