$(35$ points$)$ For a fluid flow forced into a corner, the velocity is given by:

$u=a(t)x$

$v=-a(t)y$

where a $($units: $\frac{1}{s})$ represents how fast the flow is coming into the corner. For this problem, $"$ad$"$ varies as a function of time: $a(t)=4+2sin(2t).$ Both $x$ and $y$ are in meters.

What is the equation of the streamline that goes through