The Letters R and θ Represent Polar Coordinates $$r = \cos \theta$$

Multiple Choice

The letters r and θ represent polar coordinates. Write the equation using rectangular coordinates (x, y) .
- $$r = \cos \theta$$

A) $x ^ { 2 } + y ^ { 2 } = x$
B) $x ^ { 2 } + y ^ { 2 } = y$
C) $( x + y ) ^ { 2 } = y$
D) $( x + y ) ^ { 2 } = x$