Find the slope of the tangent line to the parametric curve {x=4cos(t)y=3sin(t)\displaystyle {\left\lbrace\begin{array}{c} {x}={4}{\cos{{\left({t}\right)}}}\\{y}={3}{\sin{{\left({t}\right)}}}\end{array}\right.} at the point π3\displaystyle \frac{\pi}{{3}}