Answer:
24 inches
Step-by-step explanation:
The television is a rectangular screen, the diagonal represents the hypotenuse side while the length and height are the adjacent and opposite side in no particular order hence we can use Pythagoras theorem to find the length.
Recall that the theorem states that
opposite side^2 + adjacent side^2 = hypotenuse side^2
let the length of the television screen be L
L^2 + 18^2 = 30^2
L^2 + 324 = 900
L^2 = 900 - 324
L^2 = 576
L = √576
= 24 inches