Note that the graph of (x + 2)^2 + y^2 = 4 is a circle centered at (-2, 0) and with radius 2.
Generally, for a circle centered at (a, b) and with radius R, the polar form is (r cos θ - a)^2 + (r sin θ - b)^2 = R^2.
Can you plug in the numbers and simplify from here?