[tex]\bf (\stackrel{a}{3}~,~\stackrel{b}{-4})\impliedby \textit{now let's find the \underline{hypotenuse}}
\\\\\\
\textit{using the pythagorean theorem}
\\\\
c^2=a^2+b^2\implies c=\sqrt{a^2+b^2}
\qquad
\begin{cases}
c=hypotenuse\\
a=adjacent\\
b=opposite\\
\end{cases}
\\\\\\
c=\sqrt{3^2+(-4)^2}\implies c=\sqrt{25}\implies \boxed{c=5}[/tex]
[tex]\bf -------------------------------\\\\
sin(\theta )=\cfrac{\stackrel{opposite}{-4}}{\stackrel{hypotenuse}{5}}\qquad cos(\theta )=\cfrac{\stackrel{adjacent}{3}}{\stackrel{hypotenuse}{5}}\qquad tan(\theta )=\cfrac{\stackrel{opposite}{-4}}{\stackrel{adjacent}{3}}[/tex]