Question

In the triangle ABc, side BC is produced to D, $$\angle ACD=100^{\circ}$$ if BC=AC,then $$\angle ABC$$ is :

Answer 1

Correct option is B. $$50^{\circ}$$
In $$\triangle ABC,BC=AC\implies \angle BAC=\angle ABC$$

Given $$\angle ACD=100^{\circ}$$

As we know that

Sum of two interior angles is equal to opposite exterior angle

$$\implies \angle BAC+\angle ABC=100^{\circ}$$

$$\implies 2\angle ABC=100^{\circ}$$

$$\implies \angle ABC=\dfrac{100^{\circ}}{2}=50^{\circ}$$