P,Q P, Q\,P,Q and R R\,R lie on the circumference of a circle with centre OOO. POR POR\,POR is a diameter.

Prove that ∠PQR=90∘\angle PQR = 90^\circ∠PQR=90∘
You must not use any circle theorems in your proof.
Practise AQA GCSE Maths Proof of the Circle Theorems with exam-style questions for Foundation and Higher tier. 20 questions, matched to the AQA GCSE Maths (8300) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.