#### ShahrOZe999

##### New member

- Joined
- Sep 5, 2021

- Messages
- 1

Rϕq∙Rθq=(RN∙RM)∙(RM∙RL)=RN∙RL=RψrRqϕ∙Rqθ=(RN∙RM)∙(RM∙RL)=RN∙RL=Rrψ

Then the author says that the angle ψψ can be found out by looking at the white spherical triangle. The area of the Triangle is AA and curvature of sphere is kk so the sum of the angles θ/2+ϕ/2+(π−ψ/2)=π+kAθ/2+ϕ/2+(π−ψ/2)=π+kA so ψ=θ+ϕ−2kAψ=θ+ϕ−2kA. But this is not the formula that is written on the book. Where am i wrong?