Can a trapezoid be formed into a square and triangle?

Yes, Some can even be formed into a square and two triangles or a rectangle and one or two triangles. Just drop perpendicular(s) from the vertex (vertices) of the short side to the long side (that is to say, the two sides which are parallel). That will form one or two right triangles and a rectangle of some sort...could be a square--all squares are rectangles but not all rectangles are squares.