Sinus kąta ostrego α jest równy 4/5. Wtedy

$\displaystyle \cos\alpha= \frac{5}{4}$\displaystyle \cos\alpha= \frac{5}{4}

$\displaystyle \cos\alpha= \frac{1}{5}$\displaystyle \cos\alpha= \frac{1}{5}

$\displaystyle \cos\alpha= \frac{9}{25}$\displaystyle \cos\alpha= \frac{9}{25}

$\displaystyle \cos\alpha= \frac{3}{5}$\displaystyle \cos\alpha= \frac{3}{5}