Question

The base angles of an isosceles triangle is ${50}^o$. The size of vertical angle is

• A. ${55}^o$
• B. ${35}^o$
• C. ${70}^o$
• D. ${80}^o$

Answer 1

The correct option is D ${80}^o$

Let us consider the problem:

let the isosceles triangle, base angles are of equal measurement,

Therefore, ${50}^0$

each base angle sum of both base angle $={50}^0+{50}^0$ $=100$

sum of three angle is ${180}^0$

Find vertical angle

sum of three angle $=$ sum of base angle $+$ vertical angle

${180}^0={100}^0+$ vertical angle

vertical angle $={180}^0-{100}^0$

$={80}^0$