What is the polar form of (-200,10)(200,10)?

1 Answer
Jul 15, 2017

(10sqrt401, 3.09)(10401,3.09)

Explanation:

To convert this rectangular coordinate (x,y)(x,y) to a polar coordinate (r, theta)(r,θ), use the following formulas:

r^2=x^2+y^2r2=x2+y2
tan theta=y/xtanθ=yx

r^2=(-200)^2+(10)^2r2=(200)2+(10)2
r^2=40100r2=40100
r=sqrt40100r=40100
r=10sqrt401r=10401

tan theta=y/xtanθ=yx

tan theta=10/-200tanθ=10200
theta=tan^-1(10/-200)θ=tan1(10200)
theta~~-0.05θ0.05

The angle -0.050.05 radians is in Quadrant IVIV, while the coordinate (-200, 10)(200,10) is in Quadrant IIII. The angle is wrong because we used the arctanarctan function, which only has a range of [-pi/2, pi/2][π2,π2]. To find the correct angle, add piπ to thetaθ.

-0.05 + pi = 3.090.05+π=3.09

So, the polar coordinate is (10sqrt401, 3.09)(10401,3.09) or (200.25, 3.09)(200.25,3.09).