Find the length of the leg `x` on the right triangle below. Enter the exact value, not a decimal approximation.

[Graphs generated by this script: initPicture(-3,12+3,-3,12+3);path([[0,0],[12,0],[0,7.211102550928],[0,0]]);text([12/2,7.211102550928/2],'14','right');text([0,7.211102550928/2],'x','left');text([12/2,0],'12','below');]

`x =`