Question

The vertex angle of an isosceles triangle measures ${84}^o.$ What is the measure of base angle

• A. ${40}^o$
• B. ${42}^o$
• C. ${46}^o$
  
• D. ${48}^o$

Answer 1

Answer: (D)

${48}^o$

The vertex angle of an isosceles triangle measures ${84}^o.$
The base angles are the $2$ congruent angles in an isosceles triangle $=x+x$
Sum of the interior angles $={180}^o$

$\therefore x+x+{84}^o={180}^o$

$2x={180}^o-{84}^o$

$2x={96}^o$

$\therefore x={48}^o.$

Base angle $={48}^o$