The television is a rectangle
Diagonal is the longest side
Hypotanuse = x
Opposite = 73.9
Adjacent = 46.9
[tex]\begin{gathered} \text{Apply Pathagorus theorem} \\ \text{Opposite}^2+Adjacent^2=Hypotanuse^2 \\ 73.9^2+46.9^2=x^2 \\ 5461.21+2199.61=x^2 \\ x^2\text{ = 7660.82} \\ x\text{ = }\sqrt[\square]{7660.82} \\ x\text{ = }87.5\operatorname{cm} \end{gathered}[/tex]