TV Diagonals

The size of a television is the length of the diagonal of the viewing screen. For example, a 27" television has a viewing screen with a diagonal measurement of 27". A standard television in the United States has an aspect ratio of 4:3 ("aspect ratio" is the ratio of the width of the screen to its height). A widescreen television has an aspect ratio of 16:9.

Most programs in the US are still broadcast with a 4:3 aspect ratio. A wide screen television displays these programs by putting black bars on the edges of the screen so that the part of the screen being used has an aspect ratio of 4:3. The picture on the left shows a program broadcast in a 4:3 ratio on a screen with a 16:9 aspect ratio. The picture on the right shows a program broadcast in a 16:9 ratio, so it uses the entire screen.

Watching a regular show on a 27" widescreen television is equivalent to watching it on what size standard television?

Extra: When you watch a program broadcast in a 4:3 ratio on a widescreen TV, what percentage of the total screen area isn't being used?