In a right triangle there is only one acute angles.
one
One of them.
There is one pair of parallel sides. A trapezoid can have at most one right angle. Not all trapezoids have right angles.
A right angle only has one angle.
There are four right angles in a rectangle.
one
In a right triangle there is only one acute angles.
one.
One
one
one
Just the one
There are four right-angles (90 degrees), one in each corner of the square.
One right angle = 90 degrees so 180 degrees = 2 right angles.
One
One of them.