Suppose $sinu=x$ and $uis$ between $0$ and $\frac{}{2}.$

What $issecu?$

$\sqrt[\phantom{2}]{1-x^2}$

$\frac{x}{\sqrt[\phantom{2}]{1-x^2}}$

$\frac{\sqrt[\phantom{2}]{1-x^2}}{x}$

$\frac{1}{\sqrt[\phantom{2}]{1-x^2}}$