No, because then it would be a rectangle.
no
It would be impossible. A trapezoid can't have three right angles. It would just make a rectangle.
The sum of all four angles is 360 degrees. If three of the angles were right angles then the fourth would have to be a right angle. You would then have a rectangle or a square, but not a trapezium.
it is not possible
if a figure is a square, then it is a regular quadrilateral
No because then it would then be a square or a rectangle
Not possible - that would mean the final angle would also have to be ninety degrees - making it a square or rectangle.
It is impossible to have a triangle with 3 right angles. It is possible to draw a triangle with three right angles on the surface of a sphere: www.metacafe.com/watch/769025/270_degree_triangle_yes_3_right_angles
Yes.
Well, honey, to draw a trapezoid with no right angles, you start by drawing two parallel lines of different lengths. Then you connect the ends of those lines with two slanted lines, making sure they're not perpendicular. Voila, you've got yourself a trapezoid with all angles different from 90 degrees. Now go show off your fancy geometric skills!
No.
The sum of the interior angles of a quadrilateral is 360 degrees. If three of the angles are right angles, that is, of 90 degrees each, the the fourth must be 90 degrees. So you can have a quadrilateral with three right angles but its fourth angle will also be a right angle. So exactly 3 right angles is not possible.