I can't read that language but I'll guess it says write a second degree equation then solve for n when d=10.



Answer: n² - 3n - 20 = 0
That doesn't factor so there is no integer n solution.
That means there are no polygons with 10 diagonals.

If I’m right a triangle = 180, so 104+32 = 136. Now 180-136=44 if it’s not a answer just redo my math because at the moment I have no paper.