Question

Sendo cos(x) = 1/4 quanto vale sen (x) , parano intervalo pi < x < 3pi/2

Answer 1

$\boxed{\begin{array}{l}\sf cos(x)=\dfrac{1}{4}\longrightarrow cos^2(x)=\dfrac{1}{16}\\\sf sen^2(x)=\dfrac{16}{16}-\dfrac{1}{16}=\dfrac{15}{16}\\\\\sf sen(x)=-\sqrt{\dfrac{15}{16}}\\\\\sf sen(x)=-\dfrac{\sqrt{15}}{4}\blue{\checkmark}\end{array}}$