Converting Cartesian to Polar Coordinates: Explained with Example

[whatlifeforme]

Homework Statement

Find polar coordinates.

Homework Equations

Cartesian: (-3,4)

The Attempt at a Solution

r = sqrt(9+16) = 5
sinθ = 4/5
cosθ = -3/5

θ = ∏ - arctan(4/3)

Answer: (5, ∏ - arctan(4/3))


I do not understand why we have subtracted the value arctan(4/3) from pi?

 

[voko]

What is the range of arctan? And where is the point really located?

 

[janhaa]

Because the Cartesian coordinates (-3,4) are in 2th Quadrant