Two half-circles of the same radius sharing a common edge
Function F3D_75 returns the view factor between two half-circles that share a common edge.
The calling protocol is:
F=F3D_75(alpha)
Inputs:
alpha: angle (deg or rad)
Example:
$UnitSystem Radian
alpha=1.5 [rad]
F=F3D_75(alpha)
{Solution
F=0.273}