<Dl> <Dd> K ≤ 1 2 (a b + c d) (a c + b d) (a d + b c) 3 . (\ displaystyle \ displaystyle K \ leq (\ tfrac (1) (2)) (\ sqrt ((3)) ((ab + cd) (ac + bd) (ad + bc))).) </Dd> </Dl> <Dd> K ≤ 1 2 (a b + c d) (a c + b d) (a d + b c) 3 . (\ displaystyle \ displaystyle K \ leq (\ tfrac (1) (2)) (\ sqrt ((3)) ((ab + cd) (ac + bd) (ad + bc))).) </Dd> <P> Denoting the perimeter as L, we have </P> <Dl> <Dd> K ≤ 1 16 L 2, (\ displaystyle K \ leq (\ tfrac (1) (16)) L ^ (2),) </Dd> </Dl>

Convex pentagon with 2 parallel sides and 2 perpendicular sides