in a 25 in TV, the length of the screen a diagonal is 25 in. If the screens height is 15 in , what is its width?

Question

In a 25 in TV, the length of the screen a diagonal is 25 in. If the screens height is 15 in, what is the width ?

Answer 1

This is a good example of the Pythagorean theorem. In a right triangle, we know a^2 + b^2 = c^2, where a and b are the 2 sides joined at the right angle, and c is the hypotenuse opposite the right angle.

 

In our TV example, the hypotenuse is the diagonal line you draw across from one opposite corner to the other. the length and width are our a and b. Imagine drawing the triangle on top of a rectangle, where 2 sides match up, and the diagonal line of the triangle is the diagonal across the rectangle, corner to corner.

 

So we know from the problem that c = 25. Let's have the height of 15 be our a. Now we need to find b.

 

Plug our a and c to the pythagorean theorem:

15^2 + b^2 = 25^2

 

And solve for b:

225 + b^2 = 625

b^2 = 625 - 225 = 400

b = square_root(400)

b = 20

 

The width of the TV is 20 inches.