Trèteaux Angles: P19a-DP
 P19a-DP = Adjacent Side (Head Cut) for Rotated Purlin Rafter Bevel Angle on DP Side Of Hip Rafter on Face Set in Roof Surface
 Hip-Valley Roof Ratios Angle Formulas
- P19a-DP = arctan (cos(profile_rafter_slope_angle) ÷ tan(timber rotation angle in plan view)) + Jack Rafter Side Cut Angle  
- P19a-DP = arctan (cos(S) ÷ tan(timber rotation angle in plan view)) + P2a   
 
 
 
 
The Trèteaux Angles Formulas for Hip Rafters Rotated into the Roof Surface Plane were developed by Sim Ayers and Joe Bartok.