A rectangular LCD has an area of 480 $$cm^{2}$$ and a perimeter of 92 cm. If the size of the LCD is defined in term of length of the diagonal, then what is the size of the LCD?

Let's assume the length and breadth of a rectangular LCD is 'L' and 'B'.

A rectangular LCD has an area of 480 $$cm^{2}$$.

$$L\times B\ =\ 480$$    Eq.(i)

perimeter is 92 cm.

2(L+B) = 92

(L+B) = 46

Square on both sides.

$$(L+B)^2=46^2$$

$$L^2+B^2+2LB=2116$$

Put Eq.(i) in the above equation.

$$L^2+B^2+2\times480=2116$$

$$L^2+B^2+960=2116$$

$$L^2+B^2=2116-960$$

$$L^2+B^2=1156$$    Eq.(ii)
If the size of the LCD is defined in term of length of the diagonal, then the size of the LCD = $$\sqrt{\ L^2+B^2}$$

Put Eq.(ii) in the above equation.

= $$\sqrt{\ 1156}$$

= 34 cm