<s>[INST] Express the given polar equation in simplest rectangular form: $r = 4 + 3cosθ$ Express the given polar equation in simplest rectangular form: $r = 4 + 3cosθ$
My attempt
Multiplying r on both sides, we get
$r^2=4r+3 rcos\theta$
since, $x=rcos\theta$ and $y=rsin\theta$
and $r^2=x^2+y^2$
we get $x^2+y^2=4r+3x$
can anyone please explain after this step.. 
 [/INST] Hint: for $r\neq 0$ we get $$r=4+3\cos(\theta)$$
so you will get
$$\sqrt{x^2+y^2}=4+\frac{3x}{\sqrt{x^2+y^2}}$$
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