Rewrite the following statements in the form: 'p if and only if q'.
p: If a quadrilateral is equaiangular, then it is a rectangle.
q: If a quadrilateral is a rectangle, then it is equiangular.
Suppose ABC is an equiangular triangle. Prove that it is equilateral. (You have seen earlier that an equilateral triangle is equiangular. Thus for triangles equiangularity is equivalent to equilaterality.)