Find an equation equivalent to y = x in polar coordinates.

General flow:

1) Transform x and y to polar coordinate

2) Plug it into the orginal equation

3) Do some work to manipulate it!

From step 1, we have x = r cosθ, y = r sinθ

From step 2, we have

y = x

r sin θ = r cos θ

r (sin θ - cosθ) = 0

That means r = 0 or sinθ - cosθ = 0. You only need to play around with sinθ - cosθ = 0

Can you do step 3?