Draw a quadrilateral KLMN such that ∠K=90∘, ∠M=90∘, and ∠L=∠N.
(i) On your sketch, mark every pair of angles that are equal.
(ii) Using appropriate angle relationships, first show that the opposite angles of KLMN are equal.
(iii) Deduce that both pairs of opposite sides of KLMN are parallel and conclude that KLMN is a parallelogram.