In the figure below, lines RS and PQ intersect each other at point O. If ∠POR:∠ROQ=7:13 , find ∠SOQ.
∠ POR + ∠ ROQ = 180∘ (linear pair of angles)
∠ POR : ∠ ROQ = 7:13 (given)
∠ POR = 720 × 180∘ = 63∘
∠ ROQ = 1320 × 180∘ = 117∘
Now, ∠ POS = ∠ ROQ = 117∘ (vertically opposite angle)
And, ∠ SOQ = ∠ POR= 63∘ (vertically opposite angles)