How to calculate screen area？?

Question

I want to know how to calculate the area of a screen and the difference between 2 sizes. I want to know the area of a screen with a diagonal length of 4.3 inches and ratio of the sides are 5:3. I also need to find out the area of a 4.8 inch screen with the same ratio of the sides. I just need to know the way to do it. An answer would be nice too.

Answer 1

sqrt[(3x)^2+(5x)^2]=4.3

x= 4.3/sqrt(31)

Area=15x^2

repeat for the second one

Answer 2

Call the sides W(idth) and H(eight). You have two equations containing these two values:

W/H = 5/3, so W = 5H/3 (or H = 3W/5)

From the Pythagorean theorem, you have W^2 + H^2 = (4.3)^2 = 18.49 (or = 4.8^2 = 23.04). Now substitute from the equation above

W^2 + 9W^2/25 = 18.49. Multiply across by 25....

25W^2 + 9W^2 = 462.25

34W^2 = 462.25

W^2 = 13.596

W = 3.687

Now calculate H from the first equation and multiply the two numbers to get the area.

Repeat the process for the larger screen. OK?

  

Answer 3

you haven't said what year you're in but I'm assuming you have heard of pythagoras's theorem.

you can represent the screen as a right angles triangle with side lengths 3x 5x and 4.3

then (3x)^2 + (5x)^2 = 4.3^2

9x^2 + 25x^2 = 18.49

34x^2 = 18.49

x^2 = 0.5438235

x = 0.7374439

so the length of side one is 3*0.7374439=2.212 and the length of side 2 is 5*0.7374439=3.687

then area is simply length one * length 2 = 8.155 inches squared

the second ones the same except use 4.8 instead of 4.3