Calculus 3: Parametric curves, conic sections

Sketch the curve whose vector equation is $r(t) = \cos(t) \mathbf{i} + \sin(t) \mathbf{j} + t \mathbf{k}$.

Given the vector-valued function $r(t) = \langle 0, 3\cos(t), 5\sin(t) \rangle$, describe the curve in 3D space.

Given the vector-valued function $r(t) = \langle 6\cos(t), 0, 6\sin(t) \rangle$, describe the curve in 3D space and explain the effect of a negative $y$-component like $-t$.