For this problem, you would use the Pythagorean Theorem (a^2 + b^2 = c^2)
A and B are the length and width of the triangle. The triangle is created by the diagonal line splitting the computer screen. C is the hypotenuse, which is the diagonal line, and will always be the longest side of the triangle.
When we plug in the numbers into the formula, we would get this:
13^2 + b^2 = 15^2
B is the unknown variable in which we are trying to find. First, you square 13 and 15:
169 + b^2 = 225
Then, subtract 169 from both sides:
b^2 = 56
Finally, find the square root of both sides:
b = 7.483314774
Simplify to the nearest tenth, and the answer is 7.5<span />