Question 26
Circle TheoremsP, R and S lie on a circle centre O as shown above, while Q lies outside the circle. Find ∠PSO.
- A.35°
- B.40°
- C.45°
- D.55°
Show the answer and explanation
Answer: A (35°)
Explanation
In triangle PQR, ∠QRP = 180° − 20° − 35° = 125°, so ∠PRS = 55°. Then ∠POS = 2 × 55° = 110°, and triangle POS is isosceles, so ∠PSO = (180° − 110°)/2 = 35°.