MUST BE / COULD BE

Here are some more challenges from Mr. Quincey. For each description of a quadrilateral below, say what special type the quadrilateral must be and/or what special type the quadrilateral could be. Look out: Some descriptions may have no “must be”s, and some descriptions may have many “could be”s!  

1. “My quadrilateral has two right angles.”

   Answer (a):

   must be: none
   could be: trapezoid, rectangle, or square

2. “The diagonals of my quadrilateral are perpendicular.”

   Hint (b):

   There are no ''must be''s for part (b) either.