Question

4. Triangle ABC, Angle A = (3x + 1)Angle B = (4x- 17), and Angle C = (5x - 20)°. Which type of triangle

IS ABC?
1) equilateral
3) isosceles
2) right
4) scalene

Answer 1

3) Isosceles

Explanation:

A+B+C = 180°

(3x+1) + (4x-17) + (5x-20) = 180

12x - 36 = 180 12x = 216

x = 18

A = 3*18 + 1 = 55°

B = 4*18 - 17 = 55°

A = B