Question

what is a counterexample for the following conjecture if a counterexample does not exist choose not possible conjecture all quadrilaterals are rectangles

Answer 1

a trapezoid is a quadrilateral and it is not a rectangle

Explanation:

Answer 2

Counter example:- a trapazoid is a quadrilateral which has only one pair of parallel sides unlike a rectangle which has 2. So the conjecture is false.