Question

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In ∆ABC, side BC has been produced to D such that ∠ACD = 125° and ∠BAC = 60°. Then ∠ABC = ?



(a) 55°
(b) 60°
(c) 65°
(d) 70°

Answer 1

$$\begin{gathered} \left(c\right)65° \\ \begin{array}{l}\\ \angle \text{ACD}={125}^0\\ \angle ACD=\angle CAB+\angle ABC(\because \text{the exterior angles are equal to the sum of its interior opposite angles})\\ \therefore \angle \text{ABC}={125}^0-{60}^0={65}^0\\ \end{array} \end{gathered}$$