We will learn about the important theorems related to parallelograms and understand their proofs. Designed with Geometer's Sketchpad in mind . I'm just using some shorthand here to save some time. Reason for statement 3: Opposite sides of a parallelogram are parallel. A square is a parallelogram with four congruent sides and four right angles. pagespeed.lazyLoadImages.overrideAttributeFunctions(); for (var i=0; i