A point has rectangular coordinates $(8,-3,-1)$ and spherical coordinates $(\rho, \theta, \phi).$  Find the rectangular coordinates of the point with spherical coordinates $(\rho, -\theta, \phi).$
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
A point has rectangular coordinates $(8,-3,-1)$ and spherical coordinates $(\rho, \theta, \phi).$  Find the rectangular coordinates of the point with spherical coordinates $(\rho, -\theta, \phi).$
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
(8,3,-1)
A point has rectangular coordinates $(8,-3,-1)$ and spherical coordinates $(\rho, \theta, \phi).$  Find the rectangular coordinates of the point with spherical coordinates $(\rho, -\theta, \phi).$
train