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I assume you mean 4 congruent sides or 2 pairs of congruent sides.. (There are no 4-sided figures with 8 sides.) A square.
pentagon
Just calling it a "1000-sided shape" is fine. It is too much trouble to search for fancy name for figures with many sides.
Yes.
yes
There are none to be seen but if you meant 4 sided figures then they are quadrilaterals
Quad- or tetra-
Quadrilaterals.
4
Yes quadrilaterals are 4 sided closed figures or polygons
A parrolulegram is all 4 sided figures, and trapizoid is not a 4 sided figure?
There exists at least one quadrilateral which is not 4-sided.
A square and a rectangle are 4 sided figures each having 4 interior 90 degree angles
26
three sided figures consist of only triangles, while a four sided figure consists of any quadrilateral, so you can draw more figures with 4 sideds than with 3
a square and a rectangle. Also: trapezium trapezoid parallelogram to have a 4-sided figure, angles don't have to be 90 degrees.