The very first minimizes to Brahmagupta's system within the cyclic quadrilateral situation, due to the fact then pq = ac + bd. Take note 1: Probably the most typical trapezoids and isosceles trapezoids don't have perpendicular diagonals, but there are infinite figures of (non-very similar) trapezoids and isosceles trapezoids that https://types-of-quadrilaterals97284.full-design.com/getting-my-types-of-quadrilaterals-to-work-70039654