Question

The vertical angle of an isosceles triangle is $100°$. Find its base angles $?$

Answer 1

Finding the base angles:

We know that sum of the angles of a triangle is $180°$

In isosceles triangle base angle are equal.

Let the base angle be $\text{x}$ so we have

$\begin{array}{rcl}\Rightarrow & & \text{x+x+100°=180°}\\ \Rightarrow & & 2\text{x+100°=180°}\\ \Rightarrow & & 2\text{x=180°-100°}\\ \Rightarrow & & 2\text{x=80°}\\ \Rightarrow & & \text{x=}\frac{\text{80°}}{2}\text{=40°}\end{array}$

Hence, the base angles are $40°$.