Geometry Course/Polygon/Quadrilateral/Rectangle

Rectangle
Rectangle is a Quadrilaterl that has two long sides parallel and congruent to each other and two short sides parallel and congruent to each other and the four equal angles equal to 90o
 * Rectangle.svg
 * AD // = BC
 * AB // = DC
 * $$\angle A = \angle B = \angle C = \angle D = 90^o$$

Perimeter

 * P = AD + BC + AB + DC = 2x(a+b)

Area

 * $$A = a b$$