A certain television is advertised as a 90 inch tv (the diagonal length). If the height of the tv is 63 inches, how wide is the Tv? Round to the nearest tenth of an inch

Answer 1

TV sizes are generally advertised as the diagonal length of the TV. So think of the TV as a rectangle, we can draw a diagonal between opposite corners (say top left to bottom right) and mark that length as 90 in.

We know the height is 63 in. so we can think of this size plus the diagonal to make a right triangle

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So if the height (the left side) is 63 and the diagonal is 90

We can call the width (the bottom side)x.

Then set up a pythagorean theorem

a^2+b^2=c^2

where a = 63, b = x, c = 90

63^2 + b^2 = 90^2

3969 + b^2 = 8100

subtract 3969 from each side

b^2 = 4131

Take the square root

b = √4131 = 64.272855 = 64.3 inches (rounded to the nearest tenth)

Note: We can simplify this its divisible by 81

so √4131 = √81 * √51 = 9√51