Q9 of 29 Page 61

Find the value of x in the following figures.

Triangle AOC is a right angled triangle at O and sides AO = OC.


Hence ∠OAC = ∠OCA = y


As the sum of all angles = 180°


90 + 2y = 180


y = 45°


∠OAC = 45°


Similarly in triangle AOB


Sides AO = OB and hence


∠OBA = ∠OAB = a


As sum of all angles of a triangle = 180°


120 + 2a = 180


a = 30°


In the figure,


∠BAC = ∠CAO + ∠BAO = 45 + 30 = 75°


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