We all know the kind of clocks being used to demonstrate the time expansion in special relativity, i took one of those and rotated it so the mirrors surfaces are orthogonal to the speed vector "$V$"...
On the static system we have $\Delta t = 2L$ as always and (and here i am wrong i think but don't know why)...
$\Delta t^1=\Delta t^1 _{forward}+\Delta t^1 _{backward}=\frac{L+V\Delta t^1 _{forward}}{c}+\frac{L-V\Delta t^1 _{backward}}{c} = \frac{\Delta t}{1-\frac{V^2}{c^2}}$
Now... ...where my square root has gone? I made my algebraic calculus wrong or it's something from the beginning?
