okay for part iii this is what i did
I subbed in both the ordinates of Q and R into the eqt of the tangent
and after some algebraic work i got an expression of cos(q-p)=1/2, and cos(r-p)=1/2
then cos-1 both sides and get q-p=60, r-p=60
but adding the two equations has -2p in it:/ if it was...