Observe a figura. Usando a igualdade \(\underset{u}{\rightarrow}.\underset{v}{\rightarrow}=\frac{1}{2}\)\((\left \| \underset{u}{\rightarrow} \right \|^{2}+\left \| \underset{v}{\rightarrow} \right \|^{2}-\left \| \underset{u}{\rightarrow}-\underset{v}{\rightarrow} \right \|^{2})\), calcule o valor de \(\underset{AB}{\rightarrow}.\underset{AC}{\rightarrow}\).
Eu fiz \(\underset{AB}{\rightarrow}.\underset{AC}{\rightarrow}\)=\(\frac{1}{2}\)(6².5²-(6-(-5))²) = -30 e devia dar \(\frac{45}{2}\)
Podem ajudar-me? Obrigado
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