Answer:
Size of television screen is:
60 inches
Step-by-step explanation:
The Television screen is in the shape of a rectangle.
The size of diagonal in a rectangle is given by
[tex]diagonal=\sqrt{Length^2+Width^2}[/tex]
Here  we are given
Length=48 inches
and Width=36 inches
[tex]diagonal=\sqrt{48^2+36^2}[/tex]
[tex]diagonal=\sqrt{2304+1296}\\ \\diagonal=\sqrt{3600}\\ \\diagonal=60[/tex]
Hence, size of television screen=Length of its diagonal
                           = 60 inches