En Paraleelogram as en sjauerhuk, diar en Rütj liket, man a sidjen san ei aaltumaal likelung. A sidjen, diar jinauer lei, san oober likelung.
A = a ⋅ b ⋅ sin ( α ) = a ⋅ b ⋅ sin ( β ) = e ⋅ f ⋅ sin ( θ ) 2 {\displaystyle A=a\cdot b\cdot \sin(\alpha )=a\cdot b\cdot \sin(\beta )={\frac {e\cdot f\cdot \sin(\theta )}{2}}}
(efter Kosinussats)