In Fig. 8.125, the value of x is


Let,

AB, CD and EF intersect at O


COB = AOD (Vertically opposite angle)


AOD = 3x + 10 (i)


AOE + AOD + DOF = 180o (Linear pair)


x + 3x + 10o + 90o = 180o


4x + 100o = 180o


4x = 80o


x = 20o

10
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