Respuesta :

Answer:

It's the law of cosines

Step-by-step explanation:

law of cosines states that [tex]c^{2} =a^{2} +b^{2} -2ab (cos(\alpha ))[/tex]

so we know that a = 7, b = 4, and alpha would be 135 degrees, so just plugging it in gets us 49+16-2*7*4*(-0.707) = 65 + 39.59 = 104.59

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