Question 28
Angles and PolygonsIn the diagram above, PQT is an isosceles triangle. |PQ| = |QT|, ∠SRQ = 75°, ∠QPT = 25° and PQR is a straight line. Find ∠RST.
- A.20°
- B.50°
- C.55°
- D.70°
- E.75°
Show the answer and explanation
Answer: C (55°)
Explanation
PQ = QT, so ∠QTP = 25° and the exterior angle ∠TQR = 25° + 25° = 50°. In triangle QRS, ∠RST = 180° − 50° − 75° = 55°.