Was it really necessary to convert the centimetres to inches like that? If you can't understand metric by now, go hide under a rock
(Yeah I know it's hypocritical as I do that all the time, but shit, it's pretty easy to go use google's built in conversion engine, or just try to remember there's approx 2.5cm to the inch)
*grabs tape measure* as I sit here at my dual monitor setup, I'm 45cm from the main one and 60 from the secondary. So it would involve sitting slightly further away than I'm strictly comfortable with - or really have space for, even on a none-too-cramped desk - but it's within the realm of practicality for motion control.
However, really, at this distance I can reach out and touch the surface of both monitors without much difficulty - not stretching my arm or leaning forwards. It needs a proper fisheye lens on it so it can deal with gestures made at very nearly point-blank range. Say as little as 10cm / 4in...