## Calculus 8th Edition

The parametric equations of a circle whose radius is $r$ are given as follows: $x=r \cos t ; y =r \sin t$ From the given problem, we have $x= t \cos t , z=t \sin t , y=t$ Then, we get a circular and spiral around the y-axis for example: a helix which is away from the xz plane with the increasing radius (r).(but when $t$ decreases). This conclusion signifies the conditions indicated in the Graph (II).