Pitch angle (each base)
35°
Angle at the apex
110°
A truss is an isosceles triangle: both base angles are equal.
So apex = 180° − 35° − 35° = 110° (angle sum of a triangle).
Drag the brass dot at the apex to change the roof’s steepness. Real trusses are isosceles — both sides match — so the two base angles are equal and the apex is whatever’s left over.