Question

Obtenha o valor de x. Utilizar o teorema dos cossenos.

Answer 1

$x^{2} = 7^{2} + 8^{2} -2.7.8. cos 120^{o}$

$x^{2} = 49 + 64 -112. (- \frac{1}{2} )$

$x^{2} = 113 +56$

$x^{2} = 169$

$x = 13$