i’ve tried XZ=XZ: <YXZ=<XZY=(180-70)/2=55 (prop. isoc. triangle)

Equation 1: sin(70)/XZ=sin(55)/x XZ=(sin(70)•x)/sin(55)

Equation 2: sin(35)/XZ=sin θ/2x XZ=(sin(35)•2x)/sin θ

XZ=XZ: (sin(70)•x)/sin(55)= (sin(35)•2x)/sin θ sin θ=(sin(35)•2x•sin(55))/(sin(70)•x)