Trèteaux Angles: P20a-DP
P20a-DP = Adjacent Side (Head Cut) for Rotated Purlin Rafter Miter Angle on DP Side Of Hip Rafter on Face Perpendicular To Roof Surface, Lower Claw Angle

The Trèteaux Angles Formulas for Hip Rafters Rotated into the Roof Surface Plane were developed by Sim Ayers and Joe Bartok.