In the given figure, PQ is tangent to a circle at O and ∠BAQ=30°, show that BP = BQ.
∠BQP=∠BAQ (∠s in alternate segment are equal)
⇒∠BQP=30° ...(i) (∵ ∠BAQ=30° given)
As AB is a diameter, AQB is a Semicircle.
∠AQB=90° (angle in semicircle =90°)
From figure, ∠AQP=∠AQB+∠BQP
⇒∠AQP=90°+30°=120°
In ∆AQP, ∠QPA+∠BAQ+∠AQP=180°
⇒∠QPA+30°+120°=180°
⇒∠QPA=180°-(30°+120°)
⇒∠QPA=30° ...(ii)
From (i) and (ii) we get
∠BQP=∠QPB=30°
Therefore, QB = BP