Convert the Cartesian equation x 2 + y 2 + 2y = 0 to a polar equation.

r = -2cosθ
r = -2sinθ
r = -2cosθsinθ

Relax

Respuesta :

r2(cos2ϕ−sin2ϕ)−2rcosϕ=0r2(cos2⁡ϕ−sin2⁡ϕ)−2rcos⁡ϕ=0

r2cos(2ϕ)−2rcosϕ=0r2cos⁡(2ϕ)−2rcos⁡ϕ=0

Now
divide through by r≠0r≠0 and get

rcos−2cosϕ=0rcos⁡−2cos⁡ϕ=0

or

r=2cosϕcosr=2cos⁡ϕcos⁡2ϕ