Answer
$(3.79,-7.16)$
Work Step by Step
By definition, we know that $x=r\cdot \cos(\theta)$, $y=r\cdot \sin(\theta)$.
Here, we were given $r=8.1 \text{ and } \theta=5.2$.
Hence, after plugging these in:
$x=8.1\cdot \cos(5.2)\approx3.79$
$y=8.1\cdot \sin(5.2)\approx-7.16$
The point has coordinates $(3.79,-7.16)$ in the rectangular coordinate system.