Question

Sendo cos = 9/17' com 3 2 < < 2, determine o x​

Answer 1

$\large\boxed{\begin{array}{l}\sf cos(x)=\dfrac{9}{17}~~~~\dfrac{3\pi}{2}<x<2\pi\longrightarrow x\in~4^o~quadrante\\\\\sf cos^2(x)=\dfrac{81}{289}\\\\\sf sen^2(x)=\dfrac{208}{289}\\\\\sf sen(x)=-\sqrt{\dfrac{208}{289}}=-\dfrac{4\sqrt{13}}{17}\end{array}}$