What Are Polar Coordinates?

Instead of locating a point with:

(x,y) we locate it with (r,θ)

where:

• r = distance from the origin
• θ = angle from the positive x-axis

Think:

Cartesian = "go over x, then up y"

Polar = "go out r units at angle θ"

Converting Between Polar and Cartesian

You must memorize:

x=rcosθ y=rsinθ

and

$$ r^2=x^2+y^2 $$

$$ tanθ =y/x $$

These four formulas do almost everything.

Example: