octagon
An octagon.
An 8 sided octagon has 8 interior angles that add up to 1080 degrees
3d+8=2d-7 3d+8-8=2d-7-8 (substract 8 on both side) 3d=2d-15 3d-2d=2d-2d-15 (substract 2d on both side) d=-15
a triangle
4
square
A square
3d not = to 2d
a square
It is a rhombus or a parallelogram.
2d+8