With this problem it ask to convert r=-3 cos(theta) from polar form to cartesian
This is what I get
However the answer given is as below. What have I done wrong?
Hello,
If the polar coordinate is defined as:
x=r cos(theta)
y=r sin(theta)
then,
r=\sqrt{x^2+y^2},
cos(theta)=x/r,
sin(theta)=y/r.
By substituton,
r=-3 cos(theta) becomes
r=-3x/r that is, r^2=-3x
so that x^2+y^2=-3x.
((x+3/2)^2+y^2=(3/2)^2.)
Please adjust the above argument to the appropriate polar coordinate you are using...
Bye.
Hello,
Sorry I couldn't figure out what you had written.
Would you explain how you got these?
(If you are asked to convert r=-3 cos(theta), why begin with r=-3sin(theta)? Where does the second line come from?)
Besides, there are several ways to define coordinates.
What is the definition (in your book) of the polar coordinates?
Bye.