Answer:
a - Triangle (equilateral triangle)
b - Paralelogram
c - Square
d - Arrowhead
There is not much to explain here:
A parallelogram is a shape that isn't a square nor a rectangle but it has 2 pairs of parallel sides. Which are represented by the symbols ' and ' or " and ". Where a side named " is parallel to the other side named " and the side name ' is parallel to the other side named '.
An equilateral triangle is a triangle that has a 90º angle. In your case, the 90º angle is the one on the bottom left, represented by the symbol ∟.
Hope it helped,
BioTeacher101
