Describe the parametric equations which traces the unit circle starting (-1,0) in a clockwise direction.

Step-by-step explanation:

There are several ways we can do this.

x = cos t, y = sin t, t ≥ 0 traces the unit circle in a counterclockwise direction starting at (1, 0).

To change the direction, we can multiply one of these by -1.  Then choose an initial value of t so that the starting point is (-1, 0).

x = -cos t, y = sin t, t ≥ 0

x = cos t, y = -sin t, t ≥ π

Or, we can change the direction by switching the equations.

x = sin t, y = cos t, t ≥ 3π/2

We can also multiply both by -1:

x = -sin t, y = -cos t, t ≥ π/2

Of these four examples, I would say the first is the simplest and most straightforward, but all of them achieve the same result.