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Boa noite!
Resposta!
Só aplicar a lei dos cossenos.
![a^{2}=b^{2} +c^{2} -2.b.c.cos A\\\\\\\
a=?\\\\\
b=2Km\\\\\
c=2Km\\\\\
Cos~120\º=- \dfrac{1}{2}\\\\\\\
a^{2}=2^{2} +2^{2} -2.2.2.- \dfrac{1}{2} \\\\\\\
a^{2}=4 +4 -8.- \dfrac{1}{2} \\\\\\\
a^{2}=8 + \dfrac{8}{2} \\\\\\\
a^{2}=8 + 4 \\\\\\\
a^{2}=12\\\\\\\
a= \sqrt{12}\\\\\
\boxed{a=2 \sqrt{3}}](https://tex.z-dn.net/?f=a%5E%7B2%7D%3Db%5E%7B2%7D+%2Bc%5E%7B2%7D+-2.b.c.cos+A%5C%5C%5C%5C%5C%5C%5C%0Aa%3D%3F%5C%5C%5C%5C%5C%0Ab%3D2Km%5C%5C%5C%5C%5C%0Ac%3D2Km%5C%5C%5C%5C%5C%0ACos%7E120%5C%C2%BA%3D-+%5Cdfrac%7B1%7D%7B2%7D%5C%5C%5C%5C%5C%5C%5C%0Aa%5E%7B2%7D%3D2%5E%7B2%7D+%2B2%5E%7B2%7D+-2.2.2.-+%5Cdfrac%7B1%7D%7B2%7D+%5C%5C%5C%5C%5C%5C%5C%0Aa%5E%7B2%7D%3D4+%2B4+-8.-+%5Cdfrac%7B1%7D%7B2%7D+%5C%5C%5C%5C%5C%5C%5C++%0Aa%5E%7B2%7D%3D8+%2B+%5Cdfrac%7B8%7D%7B2%7D+%5C%5C%5C%5C%5C%5C%5C+%0Aa%5E%7B2%7D%3D8+%2B+4+%5C%5C%5C%5C%5C%5C%5C+%0Aa%5E%7B2%7D%3D12%5C%5C%5C%5C%5C%5C%5C%0Aa%3D+%5Csqrt%7B12%7D%5C%5C%5C%5C%5C%0A%5Cboxed%7Ba%3D2+%5Csqrt%7B3%7D%7D+++ "a^{2}=b^{2} +c^{2} -2.b.c.cos A\\\\\\\
a=?\\\\\
b=2Km\\\\\
c=2Km\\\\\
Cos~120\º=- \dfrac{1}{2}\\\\\\\
a^{2}=2^{2} +2^{2} -2.2.2.- \dfrac{1}{2} \\\\\\\
a^{2}=4 +4 -8.- \dfrac{1}{2} \\\\\\\
a^{2}=8 + \dfrac{8}{2} \\\\\\\
a^{2}=8 + 4 \\\\\\\
a^{2}=12\\\\\\\
a= \sqrt{12}\\\\\
\boxed{a=2 \sqrt{3}}")
![Perimetro=2+2+2 \sqrt{3}\\\\\\
Perimetro=2+2+2 (1,7)\\\\\\
Perimetro=4+3,4\\\\\\
Perimetro=7,4\\\\\\\\\
Resposta: Vai~~comprar~~7,4Km~~de~~tela.\\\\\\\
Alternativa~~C](https://tex.z-dn.net/?f=Perimetro%3D2%2B2%2B2+%5Csqrt%7B3%7D%5C%5C%5C%5C%5C%5C%0APerimetro%3D2%2B2%2B2+%281%2C7%29%5C%5C%5C%5C%5C%5C%0APerimetro%3D4%2B3%2C4%5C%5C%5C%5C%5C%5C%0APerimetro%3D7%2C4%5C%5C%5C%5C%5C%5C%5C%5C%5C%0A%0AResposta%3A+Vai%7E%7Ecomprar%7E%7E7%2C4Km%7E%7Ede%7E%7Etela.%5C%5C%5C%5C%5C%5C%5C%0AAlternativa%7E%7EC+ "Perimetro=2+2+2 \sqrt{3}\\\\\\
Perimetro=2+2+2 (1,7)\\\\\\
Perimetro=4+3,4\\\\\\
Perimetro=7,4\\\\\\\\\
Resposta: Vai~~comprar~~7,4Km~~de~~tela.\\\\\\\
Alternativa~~C")
Boa noite!
Bons estudos!
Resposta!
Só aplicar a lei dos cossenos.
Boa noite!
Bons estudos!
kamyy11:
Muito obrigado!!
De nada! Você pode fazer a mesma conta dividindo o triângulo em dois.
Mas eu teria que fazer a lei mesmo assim, né?
Não! Mas vai ter que usar uma relação trigonométrica.
Poderia me explicar por essa forma?
Acredito que esse jeito é mais fácil,pois é só substituir na formula.
Ah sim, obrigado. Já me ajudou muitoo
Dê nada!
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