Question

in triangle ABC.AB=BC and angle B=50 degree,find angle C

Answer 1

If AB = BC then angle A is equal to angle C and we will have:

$$\begin{array}{l} \angle A + \angle B + \angle C = 180{}^{\circ} \Rightarrow \\ \Rightarrow \left| \begin{array}{l} \angle B = 50{}^{\circ} \\ \angle A = \angle C \end{array} \right| \Rightarrow 2\angle C + 50{}^{\circ} = 180{}^{\circ} \Rightarrow 2\angle C = 130{}^{\circ} \Rightarrow \\ \Rightarrow \angle C = 65{}^{\circ}. \end{array}$$

Answer: $\angle C = 65{}^{\circ}$