QS bisects ∠PQR(given), m∠PQS is 45°(given), ∠PQS ≈ ∠SQR (definition of an angle bisector), m∠SQR is 45° (definition of congruent angles), ∠PQS+∠SQR=90° (addition property) 45°+45°=90° (substitution property), PQR=90°, ∠PQR is a right angle (definition of a right angle), ΔPQR is a right triangle (definition of a right triangle).
This may not be 100% what you're looking for but you can use it as a guideline. :)