Question 1131216:  Convert the polar equation to rectangular coordinates. (Use variables x and y as needed.) 
r = −3 
 Found 4 solutions by  MathLover1, ikleyn, MathTherapy, greenestamps: Answer by MathLover1(20850)      (Show Source):  Answer by ikleyn(52898)      (Show Source): 
You can  put this solution on YOUR website! . 
Convert the polar equation to rectangular coordinates. (Use variables x and y as needed.) 
r = −3 
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Traditionally, in polar coordinates, the variable " r " is the distance from the origin in a coordinate plane.
In polar coordinates, the radius r should be non-negative to describe non-empty set of points.
In your case, with r negative  r= -3, it describes EMPTY set of points.
 
 
The answer by @MathLover1 is incorrect.
 
 
 
 Answer by MathTherapy(10557)      (Show Source): 
You can  put this solution on YOUR website! Convert the polar equation to rectangular coordinates. (Use variables x and y as needed.) 
r = −3 
"r" CANNOT be negative, so IGNORE the person who claims that it can be. 
It can be 0, but not < 0. In other words,    
 Answer by greenestamps(13214)      (Show Source): 
You can  put this solution on YOUR website! 
  
I will disagree with tutors @MathTherapy and @ikleyn, both of whom say the solution is the empty set and the solution by tutor @MathLover1 is incorrect.
  
In polar coordinates, r can be negative.  (-3,pi/2) is a valid description of a point in polar coordinates; so it is a point on the graph of r=-3.
  
Any point with polar coordinates (3,theta) can be represented also by (-3,theta+pi); or with an infinite number of other representations with r equal to either 3 or -3.  So the graph of r=-3 is the same as the graph of r=3.
  
If it were the case that r can't be negative, then simple polar equations like r=sin(theta) or r = -2+cos(theta) would be invalid.
  
The equation r=-3 is independent of the angle theta; it is equivalent to the equation r=3.  Both equations are of a circle with center at the origin and radius 3.
  
As tutor @MathLover1 said, the equation in rectangular coordinates is
  
  
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