Quadrilateral Formed by Centre, Any Two Points on the Circle and Point of Intersection of Tangents
In the given ...
Question
In the given figure, AB is a diameter and AC is a chord of the circle and the tangent at C intersects AB produced in D. If ∠BAC=30∘, then find ∠CDB.
Open in App
Solution
∠ACB=90∘ (angles in the semicircle) ∠BCD=30∘ ( angles in the alternate segment are equal) [1 mark] ∠ACD=∠ACB+∠BCD =90∘+30∘=120∘ ∠CDB=180∘−(30∘+120∘) .....(sum of angles in a triangle) =180∘−150∘=30∘ [1 mark]