First off, I doubt sincerely that Mint can read the size of your physical display. It can at best indicate the resolution of your display.
Second, the problem you describe is less likely to be from Mint and more likely to be a setting of your television. You probably have your television display mode set incorrectly.
Yes, we can help you to set Mint's resolution to match your television's native resolution, but only after you have fixed your television's display to fit the native resolution.
LMDE Mate 64-bit, LM17 Mate 64-bit
Debian Xfce 64-bit, Xubuntu 14.10 64-bit, Xubuntu 14.04 64-bit, Antergos Xfce 64-bit, PCLinuxOS LXDE 64-bit