OSP=beta equal radii isosceles triangle
Opt= 90 - half alpha
Spt 90 degrees angle in semicircle
Therefore beta= half alpha, complimentary angle, angle sum of triangle,mwhatever
Gamma is 90 minus alpha cuz tangent perpendicular ok. Now
Opt equals 90 minus beta= 90 minus half alpha
Ergo
Apt= 90+ half alpha
Angle PTA= half alpha
Angler sum of triangle PTA
U now no what alpha is now find the other angles by subbing alpha in
NB: going to eat now so cannot correct working for an hour at lest if wrong. Cya guys