Question

Describe in words the surface whose equation is given. (assume that r is not negative.) θ = π/4

Answer 1

An equation in the form $\theta=\dfrac{\pi}{4}$ is the line 
that goes through the origins and whose tangent equates $\dfrac{\pi}{4}$. In general, any equation in the form $\theta=\theta_0$
is the equation of a line.