The tangent at a point A of a circle with centre O intersects the diameter PQ of the circle (when extended) at the point B. If ∠BAP = 125°, then ∠AQP is equal to:
The tangent at a point A of a circle with centre O intersects the diameter PQ of the circle (when extended) at the point B. If ∠BAP = 125°, then ∠AQP is equal to: Correct Answer 55°
Given:
A circle with center O and diameter PQ extended outside the circle to point B
∠BAP = 125°
Concept Used:
Angle formed between radius and tangent of a circle is always 90°
Angles opposite to equal sides are equal.
Sum of two opposite interior angles of a triangle is equal to the opposite exterior angle.
Sum of all angles of triangle is 180°
Calculation:
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OA ⊥ BA (Angle between Radius and Tangent)
∠OAP = ∠BAP - ∠OAB
⇒ ∠OAP = 125° - 90° = 35°
Since,
OA = OP = OQ (Radius of circle)
So,
∠OAP = ∠OPA = 35°
∠AOQ = ∠OAP + ∠OPA
⇒ ∠AOQ = 35° + 35° = 70°
In Δ AOQ,
∠AOQ = 70°
∠OAQ = ∠OQA (since OA = OQ)
∠AOQ + ∠OAQ + ∠OQA = 180°
⇒ 70° + ∠OAQ + ∠OQA = 180°
⇒ ∠OAQ + ∠OQA = 180° - 70° = 110°
⇒ 2∠OQA = 110°/2 = 55°
Since ∠OQA is the same angle as ∠AQP
∠AQP = 55°
∴ The value of ∠AQP = 55°