Square Cut Fascia intersects foot of Hip Rafter
Developments of Compound Angles

Tetrahedron of the Compound Angle ... Main Side Square Fascia
Development of Compound Angle ... Main Side Fascia
Development of Compound Angle ... Adjoining Side Fascia

Proof of Saw Blade Bevel along the miter line of the Main Side Sheathing Angle

Trigonometric Proof of the Saw Blade Bevel along the miter line of the Main Side Sheathing Angle
Using the same reasoning, we can show that the Saw Blade Bevel along
the miter line of the Adjoining Side Sheathing Angle, 90° – P2a, is:
arctan (sin R1 / tan DD) = C5m ... the Main Side Backing Angle

Proof of ... cos P2 = sin R1 ÷ sin SS

Proof of cos P2 = sin R1 ÷ sin SS
Joe Bartok