PQR is a right angle triangle. QS is perpendicular to PR, and PQ has length 1.
1) Find QS and PS in-terms of 0.
2) By considering triangle QSR, find an expression for SR.
3) By considering triangle PQR, find PR in-terms of e.
4) Hence, show that
cos A = sec 0 -sin o tan 0.
Some one please help me I'm stuck on this question.