How do you convert (-4,-4)(4,4) into polar form?

1 Answer
Mar 10, 2018

(4sqrt2, 225°)

Explanation:

To convert between polar and rectangular, these formulas will help you out. (Link to the webpage I got the image from is in gray.)

![http://www.mathwords.com/p/polar_rectangular_conversion_formulas.htm](useruploads.socratic.org)

So we can see that where the Cartesian/rectangular ordered pairs follow the (x, y) format, polar ordered pairs follow (r, theta).

The steps here can vary, depending on whether you want to find theta or r first, but we'll just find theta first for this answer.

tantheta = (-4)/-4 = 1
arctan(1) = 45°

We should note, however, that since x and y are both negative, our point is in quadrant III. 45° is just the reference angle. theta is actually 225°.

We can use one of the left-hand formulas to find r now.

-4 = rcos225°

-4 = r((-sqrt2)/2)

r = -4 * 2/(-sqrt2) = (-8)/(-sqrt2) = (-sqrt2^6)/(-sqrt2) = sqrt2^5 = 4sqrt2

So we have found our answer: (-4, -4) in polar form is (4sqrt2, 225°).

Of course, the way you write your answer is going to depend on whether they want theta in radians or degrees and whether they want you to be exact with r or round, but you get the gist, hopefully.