Question 860530
Polar coordinates usually involve {{{r}}} and {{{theta}}} ,
while for rectangular coordinates we usually use {{{x}}} and {{{y}}} .
To relate them we have
{{{x=r*cos(theta)}}} , {{{y=r*sin(theta)}}} ,
{{{r=sqrt(x^2+y^2)}}} , and {{{tan(theta)=y/x}}}
 
{{{r(sin(theta) + 3cos(theta)) = 4}}}
{{{r*sin(theta) + 3*r*cos(theta) = 4}}}
{{{y + 3*x = 4}}}
{{{highlight(3x+y=4)}}}