question_answer

In \[\Delta ABC,\]If \[AB=BC\] and \[\angle B=40{}^\circ ,\]what is the measure of \[\angle C\]?

A) \[70{}^\circ \]         

B)  \[80{}^\circ \]           

C)  \[130{}^\circ \]                        

D)  \[40{}^\circ \]

Correct Answer: A

Solution :

(a): It is isosceles \[\Delta le\text{ }\Rightarrow x+x+40{}^\circ =180{}^\circ \] \[\therefore \,\,x=70{}^\circ \]