## anonymous one year ago Which set of polar coordinates describes the same location as the rectangular coordinates (1,-1)? A. (-1, 135 degrees) B. (sqrt(2) , 315 degrees) C. (1, 45 degrees) D. (sqrt(2) , 225 degrees) ***My Answer: A*** Is this correct?

1. LynFran

B

2. anonymous

Why is that?

3. misssunshinexxoxo

r is sqrt(2). positive r and -45 degrees or +315 degrees. use negative r and 135 degrees.

4. misssunshinexxoxo

B is initially correct:)

5. LynFran

$r ^{2}=x ^{2}+y ^{2}$ so, $1^{^{2}}+(-1)^{2})=r ^{2}$$r=\sqrt{2}$

6. anonymous

Oh I see now! Thank you guys for the help : )

7. LynFran

$\tan^{-1} \frac{ -1 }{ 1 }=45$ subtract 45 from 360 u get 315

8. anonymous

Ohhh that's what I was doing wrong. Thanks for helping me understand!