Question

In a $△ABC$ with $AB=AC$, $\angle A+\angle B={145}^o$, then $\angle A$ equals.

• A. ${110}^o$
• B. ${80}^o$
• C. ${35}^o$
• D. ${100}^o$

Answer 1

The correct option is A ${110}^o$

$AB=ACor\angle C=\angle B$
We know that
$\angle A+\angle B+\angle C={180}^o$
Substituting the given values, we get
${145}^o+\angle C={180}^o$
$or\angle C={35}^o=\angle B$
$or\angle A+{35}^o={145}^o$
$\therefore \angle A={110}^o$