In the diagram, O is the centre of the circle where OS//QR and ∠SOR = 35o
A.
35o
B.
45o
C.
55o
D.
70o
Correct answer is C
∠SOR = ∠ORQ alternate angle.
Also ∠OQR = ∠OQR (Base angle of isosceles)
∠QOR = 108 – 2(35o) = 180 - 70o - 110o ∠QPR = 1/2QOR = 1/2(110o) ∠QPR + 55o (theorem angle at center is twice angle at circumference)