Question

Dado sec x = √2/3, determinar cos x.

Answer 1

Temos que, $\text{sec}~x=\dfrac{1}{\text{cos}~x}$.

Deste modo, como $\text{sec}~x=\dfrac{\sqrt{2}}{3}$, segue que:

$\dfrac{1}{\text{cos}~x}=\dfrac{\sqrt{2}}{3}$.

Logo, $\text{cos}~x=\dfrac{3}{\sqrt{2}}=\dfrac{3\sqrt{2}}{2}$.