Chapter 10.2, Problem 9ES

Identify the curve by transforming the given polar equation to rectangular coordinates.

$\begin{array}{l}\left(\text{a}\right)r=2\\ \left(\text{b}\right)r\sin \theta =4\\ \left(\text{c}\right)r=3\cos \theta \\ \left(\text{d}\right)r=\frac{6 }{3\cos \theta +2\sin \theta }\end{array}$