Question

10. The base angle of an isosceles triangle is 20 more than thrice the vertex angle. Find

the value of equal angles​

Answer 1

Dear friend, Here is your answer:

Let each of the base angles be x

Let the vertex angle be y

According to question

2x = 20+3y

2x - 3y = 20............ (i)

x+x+y = 180° (Angle sum property of a triangle)

2x + y = 180°............. (ii)

Subtracting (i) from (ii)

  2x + y = 180

  2x - 3y = 20

(-)       (+)      (-)

4y = 160

y = 40

Substituting y=40 in equation (ii)

2x + 40 = 180

2x = 180 - 40

x = 140/2

x = 70

Therefore, value of the equal base angles is 70°

Hope this answer helps you out

Best of luck : )