A 70-inch LED TV is usually about 61 inches tall and 34.25 inches wide. Most HD televisions have a 16:9 aspect ratio; the advertised television size measures the diagonal distance between two opposite corners of the TV.
The diagonal distance between two corners of the television is always than the height or the width of the TV.
A TV that is twice as large as a smaller TV when measured diagonally has more than four times the total viewing area, assuming both TVs have the same aspect ratio. A 70-inch TV is nearly twice as large as a 50-inch TV.