The height of a parallelogram must be perpendicular to its base, the base of this parallelogram can only be 13 inches and the height is 18 inches. Since the side lengths are not straight lines the height must be found using this method.
The height of a triangle, parallelogram and trapezoid must have a height that is perpendicular to its base. Whereas it can be found by extending the length of the base or straightening the side length that is to be the height creating a right angle.
