Answer
A circle center at the origin (0,0) with radius $1$.
Work Step by Step
Conversion of polar coordinates and Cartesian coordinates are as follows:
a)$r^2=x^2+y^2 \implies r=\sqrt {x^2+y^2}$
b) $\tan \theta =\dfrac{y}{x} \implies \theta =\tan^{-1} (\dfrac{y}{x})$
c) $x=r \cos \theta$ d) $y=r \sin \theta$
Since, $r^2=x^2+y^2$, the Cartesian equation is $x^2+y^2=1$
This shows a circle centered at the origin (0,0) with radius $1$.
