Question

How do you convert `r = 4cos(theta)` into rectangular form?

Answer 1

`(x-2)^2 +y^2=4`

Explanation:

`r=4costheta`
`r^2=4rcos theta`-> multiply both sides by r
`x^2+y^2 = 4x`-> substitute in `x^2+y^2` for `r^2` and `x` for `rcos theta`
`x^2-4x+y^2=0`-> combine like terms
`(x-2)^2+y^2=4`->complete the square