If the polar coordinates of the point ( x , y ) are ( r , θ ), determine the polar coordinates for the following points. (Use any variable or symbol stated above as necessary.)

a) -x,y
b)-2x,-2y
c)3x,-3y

I don't understand what they are asking for because i tried the r=sqrt(x^2+y^2) and that theta = tan^-1(y/x) and it was wrong.

Question

If the polar coordinates of the point ( x , y ) are ( r , θ ), determine the polar coordinates for the following points. (Use any variable or symbol stated above as necessary.)

a) -x,y
b)-2x,-2y
c)3x,-3y

I don't understand what they are asking for because i tried the r=sqrt(x^2+y^2) and that theta = tan^-1(y/x) and it was wrong.

vincent-lyon.fr · Answer

Draw a picture with x, -x, -2x, 3x, y, -3y  etc.

anonymous · Answer

You need to realize that the points that you are given are not generic...they are translations of the original point $(x,y)$, which you are told have polar coordinates $(r,\theta)$.  Go with the hint above, but also plot $(x,y)$ and $(r,\theta)$, and see if you can reason out the other polar coordinates using that information.