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}}}
(ley de cosenos)
e = a 2 + b 2 + 2 ⋅ a ⋅ b ⋅ cos ( α ) {\displaystyle e={\sqrt {a^{2}+b^{2}+2\cdot a\cdot b\cdot \cos(\alpha )}}}