"...need to be the same SIZE?" Quadrilateral (including trapezium).
An isosceles trapezoid has 2 sides that are the same length.
Only two of the three sides need to be the same size in an isosceles triangle.
Sides that are the exact same size
I guess you mean with ALL sides the same size it's an equilateral triangle
No. All of a square's sides are the same size.
Their 3 sides must equal each other and have the same size angles.
Four sides of the same size.
Its simple, You need 2 ends the same size, 2 sides the same size, you can nail, or glue, or both, together, once together cut a bottom to fit the size of the ends & sides. if you want a top, do the same as you did for the bottom and attach hinges. Good-Luck
Yes,all of the sides of a polygon are the same shape.
No, you need both pairs of opposite sides to be congruent (i.e. the same size) to be a parallelogram.