You can have the labels vertical (right click on the axis > format > Alignment > up or down) but not at an angle as in your image.
so is it in Tableau 10.0
Can we use trigonometric function to rotate the labels/headers? I am not aware of using trigonometric functions in tableau.
It's not an option added to v10 (at least not in the beta version I have).
I think because it's not considered to be visual best practice (which tableau tries to guide users to) they haven't been added to the tool.
Ashish - there's no doubt a clever workaround using trig however I imagine you'd need a separate worksheet below the chart to house the labels. That sounds to me like one of those things that can be achieved in tableau but probably doesn't need to be!