Answer:
The Pythagorean theorem only works for right triangles. This is not a right triangle.
x = 23
All interior angles of a triangle = 180 degrees.
A + B + C + 180
(3x) + (2x+12) + (2x+7) = 180
7x + 19 = 180
7x = 161
x = 23
A = 3(23) = 69 degrees
B = 2(23) + 12 =58 degrees
C = 2(23) + 7 = 53 degrees
