SOLUTION: Convert to polar: (x+2)² + y² = 4 A.) r = 4cosΘ B.) r =-4cosΘ C.) r = 4sinΘ D.) r =-4sinΘ

Algebra ->  Test -> SOLUTION: Convert to polar: (x+2)² + y² = 4 A.) r = 4cosΘ B.) r =-4cosΘ C.) r = 4sinΘ D.) r =-4sinΘ      Log On


   

Question 1079667: Convert to polar: (x+2)² + y² = 4
A.) r = 4cosΘ
B.) r =-4cosΘ
C.) r = 4sinΘ
D.) r =-4sinΘ
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

reminder:
x=+r%2Acos%28theta%29
y=+r%2Asin%28theta%29
if
%28x%2B2%29%5E2%2By%5E2=4, than we have
%28r%2Acos%28theta%29%2B2%29%5E2%2B%28+r%2Asin%28theta%29%29%5E2=4
r%5E2%2Acos%5E2%28theta%29%2B4r%2Acos%28theta%29%2B4%2B+r%5E2%2Asin%5E2%28theta%29=4
r%5E2%2Acos%5E2%28theta%29%2B4r%2Acos%28theta%29%2B+r%5E2%2Asin%5E2%28theta%29=4-4
r%5E2%2Acos%5E2%28theta%29%2B+r%5E2%2Asin%5E2%28theta%29%2B4r%2Acos%28theta%29=0
r%5E2%28cos%5E2%28theta%29%2B+sin%5E2%28theta%29%29=-4r%2Acos%28theta%29
r%5E2=-4r%2Acos%28theta%29
r%5Ecross%282%29=-4cross%28r%29%2Acos%28theta%29
r=-4%2Acos%28theta%29

answer:B.) r =-4cosΘ