Question

Determine o valor de x na figura.





Lei dos senos e cossenos​

Answer 1

Utilizando a lei dos cossenos, temos:

$\boxed{a^2~=~b^2+c^2-2\cdot b\cdot c\cdot cos(\hat{A})}\\\\\\x^2~=~3^2+8^2-2\cdot 3\cdot 8\cdot cos(60^\circ)\\\\\\x^2~=~9+64-2\cdot3\cdot8\cdot\dfrac{1}{2}\\\\\\x^2~=~73-24\\\\\\x^2~=~49\\\\\\x~=~\sqrt{49}\\\\\\\boxed{x~=~7}$