Question

In a ∆ABC , angle A + Angle B = 125° and Angle B + Angle C = 150° . Find all the angles of ∆ABC.​

Answer 1

Answer:

angle A=30°

angle B=95°

angle C=55°

Answer 2

$\large\underline{\sf{Solution-}}$

Given that,

In triangle ABC

$\purple{\rm :\longmapsto\:\angle A + \angle B = 125 \degree \: - - - (1) }$

$\purple{\rm :\longmapsto\:\angle B + \angle C = 150 \degree \: - - - (2)}$

We know,

Sum of all interior angles of a triangle is supplementary.

$\purple{\rm :\longmapsto\:\angle A + \angle B + \angle C = 180\degree }$

On adding equation (1) and (2), we get

$\purple{\rm :\longmapsto\:\angle A + \angle B + \angle B + \angle C = 125\degree + 150 \degree \:}$

$\purple{\rm :\longmapsto\:\angle A + \angle B + \angle C + \angle B = 275\degree \:}$

$\purple{\rm :\longmapsto\:180\degree + \angle B = 275\degree \:}$

$\purple{\rm :\longmapsto\:\angle B = 275\degree - 180\degree \:}$

$\purple{\rm :\longmapsto\:\angle B = 95\degree \:}$

On substituting the value in equation (1) and (2), we get

$\purple{\rm :\longmapsto\:\angle A + 95\degree = 125\degree }$

$\purple{\rm :\longmapsto\:\angle A = 125\degree - 95\degree }$

$\purple{\rm :\longmapsto\:\angle A = 30\degree }$

Also, from equation (2), we get

$\purple{\rm :\longmapsto\:95\degree + \angle C = 150\degree }$

$\purple{\rm :\longmapsto\:\angle C = 150\degree - 95\degree }$

$\purple{\rm :\longmapsto\:\angle C = 55\degree }$

Hence,

$\begin{gathered}\begin{gathered}\bf\: \rm\implies \:\begin{cases} &\sf{\angle A = 30\degree } \\ \\ &\sf{\angle B = 95\degree } \\ \\ &\sf{\angle C = 55\degree } \end{cases}\end{gathered}\end{gathered}$