Reposted under Physics...

I've tried for hours to solve for v, but can't get the rearranging right.

I'm using

L= Lo sqrt 1- v^2/c^2

Can anyone suggest the first couple of steps?

I can get the answer by the way, by substituting values 'til I get the contracted length. Original and final length are given.

Thanks

What do you get if you square both sides?