In the diagram, O is the centre of the circle where

In the diagram, O is the centre of the circle where OS//QR and ∠SOR = 35^o

• A. 35^o
• B. 45^o
• C. 55^o
• D. 70^o

Correct Answer: Option C

Explanation

∠SOR = ∠ORQ alternate angle.

Also ∠OQR = ∠OQR (Base angle of isosceles)

∠QOR = 108 – 2(35^o) = 180 – 70^o – 110^o ∠QPR = ¹/₂QOR = ¹/₂(110^o) ∠QPR + 55^o (theorem angle at center is twice angle at circumference)