Nie istnieje kąt ostry α taki, że

$\displaystyle \sin\alpha= \frac{1}{3}$\displaystyle \sin\alpha= \frac{1}{3} i $\displaystyle \cos\alpha= \frac{2}{3}$ \displaystyle \cos\alpha= \frac{2}{3}

$\displaystyle \sin\alpha= \frac{5}{13}$\displaystyle \sin\alpha= \frac{5}{13} i $\displaystyle \cos\alpha= \frac{12}{13}$ \displaystyle \cos\alpha= \frac{12}{13}

$\displaystyle \sin\alpha= \frac{3}{5}$\displaystyle \sin\alpha= \frac{3}{5} i $\displaystyle \cos\alpha= \frac{4}{5}$ \displaystyle \cos\alpha= \frac{4}{5}

$\displaystyle \sin\alpha= \frac{9}{15}$\displaystyle \sin\alpha= \frac{9}{15} i $\displaystyle \cos\alpha= \frac{12}{15}$ \displaystyle \cos\alpha= \frac{12}{15}