10. The length of the curve $\left\{\begin{array}{l}x=2 \cos ^{2} \theta \\ y=3 \sin ^{2} \theta\end{array}\right.$ ( $\theta$ is the parameter) is
10. $\sqrt{13}$ Hint: Eliminating the parameter yields $\frac{x}{2}+\frac{y}{3}=1(0 \leqslant x \leqslant 2)$, which is a line segment, with a length of $\sqrt{13}$.