[tex]\bf 9x+y=10\qquad
\begin{cases}
x=rcos(\theta)\\
y=rsin(\theta)
\end{cases}\quad thus\quad 9rcos(\theta)+rsin(\theta)=10
\\\\\\
\textit{polar equations are in }\theta\textit{ terms, thus}
\\\\\\
r[9cos(\theta)+sin(\theta)]=10\implies r=\cfrac{10}{9cos(\theta)+sin(\theta)}[/tex]
