In the diagram, O is the centre of the circle where OS//QR and ∠SOR = 35º. Find the value of ∠QPR.
Attached Figure / Diagram
A
35o
B
45o
C
55o
D
70o
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
∠SOR = ∠ORQ alternate angle.
Also ∠OQR = ∠OQR (Base angle of isosceles)
∠QOR = 180 – 2(35º) = 180 - 70º = 110º, ∠QPR = 1/2QOR = 1/2(110º) ∠QPR = 55º (theorem angle at center is twice angle at circumference)
Source: Myschool Past Questions Archive (Record #26648)