Convert the rectangular equation to a polar equation that ex
     Convert the rectangular equation to a polar equation that expresses r in terms of theta.  x^2 + (y + 2)^2 = 4  r =  (Type an expression in terms of theta.) 
  
  Solution
Solution:
to convert into polar coordinate
plug x = rcos()
y = rsin()
x2+ (y+2)2 = 4
(r cos())2 + (rsin() +2 )2 = 4
r2 cos2() + r2sin2() + 2rsin() +4 = 4
r2 ( cos2() + sin2() ) + 2 r sin() = 0
r2 + 2rsin() =0
r = 0
r = - 2sin()
r =0 is not possible
therefore
Answer: r = -2sin()

