Can a rhombus be inscribed in a circle? Why or why not?
No you can not inscribe a rhombus inside a circle. The necessary and sufficient conditions for a quadrilateral to be rhombus is that it should have perpendicular and unequal diagonals. When you inscribe a quadrilateral in a circle you are bound to get equal diagonals (which will be equal to diameter of circle). So no you can not inscribe a rhombus inside a circle.