Question

If each of the equal angles of an isosceles triangle measure 25 degrees less than twice the vertex angle, what would the vertex triangle measure?

Answer 1

let the vertex angle be x

each base angles is 2x - 25,

sum of angle in triangle is 180

therefore

x + 2x - 25 + 2x - 25 = 180

5x - 50 = 180

5x = 180 + 50

5x = 230

x = 230/5 = 46°

base angles are 2x - 25

= 2 × 46 - 25

= 92 - 25

= 67°

vertex angle = 46°