Answer
$$r=\frac{2}{cos\theta + sin \theta}$$
Work Step by Step
As we are given that $x+y=2$
To convert this equation into polar equation, we will substitute $x=rcos\theta$ and $y=rsin \theta$
Thus, $$rcos\theta + rsin \theta =2$$
or $$r=\frac{2}{cos\theta + sin \theta}$$
