In einem rechtwinkligen Dreieck gilt:

$\sin (\alpha )={\displaystyle \frac{\text{Gegenkathete}}{\text{Hypotenuse}}}={\displaystyle \frac{\mathrm{\mid }\overline{BC}\mathrm{\mid }}{\mathrm{\mid }\overline{AC}\mathrm{\mid }}}\backslash sin\; (\backslash alpha\; )=\backslash dfrac\{\backslash text\{Gegenkathete\}\}\{\backslash text\{Hypotenuse\}\}=\backslash dfrac\{|\backslash overline\{BC\}|\}\{|\backslash overline\{AC\}|\}$