An equilateral triangle.
No, both shapes have all four sides equal.
A regular polygon has all sides equal length, and all of the angles are equal.
The only similarities between these shapes are that:These shapes have all congruent interior anglesObviously, the shapes are regular and have equal sides.
not really a square and a diamond does
A rhombus is the only shape besides a square that can have equal sides.
It isn't really a square if it has no equal sides. A trapezoid can be drawn that has no equal sides, some can have two sides equal. Quadrilaterals include those 4-sided shapes with no sides equal but they also include all other 4-sided shapes. You would need to specify "Quadrilateral with no equal sides".
Regular shapes are shapes where all the sides and angles are equal. One example of a regular shape is a square because all the sides are the same and all the angles are 90 degrees.
It is a square as square has 4 sides and all of them are equal. Also it has 4 corners.