Q. In the given figure, AB is the diameter and ∠ ADC = 2 times ∠ BDC. If ∠ BCD = 70 ° , then find the angle made by AC at the centre of the circle. Share with your friends Share 2 Varun Rawat answered this Let ∠BDC = x, then ∠ADC = 2xNow, ∠ADC + ∠BDC = 180° Linear pair⇒2x + x = 180°⇒3x = 180°⇒x = 60°So, ∠BDC = 60°Now, in ∆DCB,∠BDC + ∠BCD + ∠CBD = 180° Angle sum property⇒60° + 70° + ∠CBD = 180°⇒∠CBD = 50°Now, angle subtended by an arc at the centre is double the angle subtended by same arc at any point on the circle.So, ∠AOC = 2∠ABC = 2×50° = 100° 0 View Full Answer Ansuman answered this 4cm -2 Aditya Singh answered this Stop guessing. How could an angle's measure be 4cm? -1