Question

How would you name a sorting rule for 1 square, 1 rectangle, 1 triangle

Answer 1

If the shape has 4 equivalent sides and all angles add up to be 360 degrees, then it is a square.
If the shape has 2 pairs of equivalent sides and all angles add up to be 360 degrees, then it is a rectangle.
If the shape has 3 sides and all angles add up to be 180 degrees, then it is a triangle.