## anonymous 5 years ago Parametrize a disk of radius a which lies on the yz plane and is oriented clockwise when viewed from the positive x-axis.

1. anonymous

I'm not too sure about what you mean by 'oriented clockwise'. I'm going to assume you mean that the position vector rotates clockwise when we view down along the positive x-axis. If the disk lies in the y-z plane, with y horizontal and z vertical, then the position vector will be, $(y,z)=({a}\cos(-{\theta}),{a}\sin(-{\theta}))=({a}\cos({\theta}),-{a}\sin({\theta}))$Setting

2. anonymous

$\theta \rightarrow -{\theta}$will allow the position vector to rotate clockwise as you increase theta. I hope this is what you're looking for.

3. anonymous

Yes, thank you.