The temperature at a point $(x,y)$ on a fat metal plate is given by $(x,y)=\frac{65}{(2+x^2+y^2)},$ where T is measured in $C$ and $x,y$ in mesers. Find the rate of crange of timperature $?\frac{C}{m}$ weth respect to distance at the point $(1,3)$ in the $x-$directian and the $y-$direction.

$($a$)$ the $x-$direction

$"\frac{C}{m}$

$($b$)$ the v$-$diftection

$\frac{C}{m}$