Solve {l}{4-4t+t^2=9-9t^2}{a=sqrt{1-t^2}}

$$\left. \begin{array} { l } { 4 - 4 t + t ^ { 2 } = 9 - 9 t ^ { 2 } } \\ { a = \sqrt { 1 - t ^ { 2 } } } \end{array} \right.$$

Solve for t, a

$$t=-\frac{3\sqrt{6}}{10}+\frac{1}{5}\approx -0.534846923\text{, }a=\frac{\sqrt{6}}{10}+\frac{3}{5}\approx 0.844948974$$

$$t=\frac{3\sqrt{6}}{10}+\frac{1}{5}\approx 0.934846923\text{, }a=-\frac{\sqrt{6}}{10}+\frac{3}{5}\approx 0.355051026$$