Points M and N are two of the vertices of a right triangle. They are the endpoints of the hypotenuse MN¯¯¯¯¯¯¯ of the triangle. The third vertex lies in the fourth quadrant.

Plot a point at the location of the third vertex.

I don't understand why I keep getting this question wrong. Should the points be connected by lines? Is there something else to do?
If anyone has taken this test before, do you only plot a point, or do you connect the points or do something else too?