According to the exterior angle theorem , the exterior angle of a triangle is equal to the sum of the two opposite interior angles
So
9x - 26 = (2x -12) + (4x + 43)
9x - 26 = 6x + 31
3x = 57
x = 19
Plug in x = 19 to find Answer: m
119> 90 is an obtuse angle so of course, it is an obtuse triangle
