A:Answer Indeed, the horizontal & vertical dimensions CANNOT BE 4.8" & 14.9". If the 16:9 aspect ratio is correct (1920 x 1080 ... ) then a 21.5" screen would have to have a horizontal dimension of 18.74" & a vertical dimension of 9.18" (the ratio of the diagonal (hypoteneuse) with that aspect ratio).
My answer is that the ACER Techs were asleep at the wheel, & they ignored your question. Maybe somebody will try harder this go 'round... :) :D :P