The answer is a trapezoid.
a trapezoid
it is a right angled trapezium
The shape can only be a rectangle! A rectangle is a four-sided 2-dimentional figure, where every angle is a right angle, opposite sides are parallel, but the 4 sides are NOT equal.
a square
It is a square.
A rectangle
A right angle has no parallel lines, but it does have perpendicular lines that meet at right angles.
It could be a right angle triangle
As defined, a quadrilateral. Could be others, but need to know about parallel and/or equal sides...
a right angle triangle.
It could be a trapezoid providing that the other two angles are an acute angle and an obtuse angle
that doesn't make sense. At least not to me...