Q14 of 29 Page 61

In the figure at right, ABCD is a cyclic quadrilateral in which ∠BCD = 100°and ∠ABD = 50°. Find ∠ADB

As ABCD is a cyclic quadrilaterals, sum of all angles = 360°


As angle subtended by chord BD on circumference = 100°


Therefore ∠DAB = 100°


As sum of all angles of triangle ADB is 180°


Hence ∠ADB = 180–50–100 = 30°


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