If we have a right triangle R as:
We have a right angle.
The only way we can make a parallelogram that is not a square is placing the triangle so the parallelogram does not have any right angle. That would be;
This way, the right angles are added to one of the other angles, in order to have none right angles, as it is the condition to have a four-side figure that is not a square or rectangle.
(If the triangle R can compose a square, it should have two equal sides, not like our figure).