Question

What is the polar form of `( 0,-9 )`?

Answer 1

`9/_-pi/2`

Explanation:

Any point `(x,y)` in rectangular form may be converted into polar form `(r, theta)` as follows

`r=sqrt(x^2+y^2)`

`theta=tan^(-1)(y/x)`

Where `theta` is always measured anti-clockwise from the positive x-axis.

So in this case, `r=sqrt(0^2+9^2)=9`

Since this point `(0,-9)` lies on the negative y-axis, its angle from the positive x-axis is `-90^@ or -pi/2` radians