By the Triangle Angle-Sum Theorem, all the angles of a triangle have to add up to equal 180. If two of the angles are the same, then we will call them x. The third one is 39 more than the measure of each of the other angles, so the third angle measures x + 39. In equation form,
x + x + x + 39 = 180 and
3x + 39 = 180 and
3x = 141 so
x = 47
That means that the largest angle measures 47 + 39 which is 86
