Parallelogram.
It is an isosceles trapezoid.
Trapezoid.
trapezoid
A quadrilateral with 4 equal sides but not a trapezoid is called a rhombus. In a rhombus, opposite sides are parallel but there are no right angles.
trapezoid
rhombus, trapezoid
A trapezoid can't have three right angles. A quadrilateral with three right angles must have a total of four right angles, since a quadrilateral's interior angles add up to 360. 360 - (3*90) = 90, so the fourth angle would have to be right as well. A quadrilateral with four right angles is not a trapezoid; instead it is a rectangle or a square.
A quadrilateral that has one (and only one) pair of parallel sides is a trapezoid. It is isosceles of the non-parallel sides are of equal length. It is right angled if any one of the angles is 90 degrees.
trapezoid
A quadrilateral with 0 right angles is a trapezoid, i know it looks like it has right angles IT DOES NOT!
An isosceles trapezoid will have diagonals of equal length but will never contain right angles by definition. A square and rectangle will have diagonals of equal length but will contain 4 right angles. A rhombus and any other parallelogram that does not contain right angles will not have diagonals of equal length.
Trapezoid