The curve γ(t)=[(u(t),v(t)]=[e^{λt},t]

lies on the cone parametrized by:

σ(u,v)=[ucos z,usin v,u]

show that the curve intersects each of the rulings of the cone at the same

angle.

i get that a surface that is the union of straight lines is a ruled surface and that the lines are the rulings, but i cannot figure out how to find the rulings of any surface.