Question 936569
<pre>
The polar substitutions are:

{{{x/r=cos(theta)}}} -> {{{x=r*cos(theta)}}}
{{{y/r=sin(theta)}}} -> {{{y=r*sin(theta)}}}
{{{r^2=x^2+y^2}}} -> {{{r=sqrt(x^2+y^2)}}}

{{{x = 5}}}

{{{r*cos(theta)=5}}}

{{{r=5/cos(theta)}}}}}}

{{{r=5*sec(theta)}}}

Edwin</pre>