Answer:
[tex]D = 42.5\ inch[/tex]
Step-by-step explanation:
Given
[tex]L = Length[/tex] and [tex]W = Width[/tex]
[tex]L:W = 8: 5[/tex]
[tex]Perimeter = 117[/tex]
Required
Determine the Diagonal
First, the dimension of the screen has to be calculated;
Recall that; [tex]L:W = 8: 5[/tex]
Convert to division
[tex]\frac{L}{W} = \frac{8}{5}[/tex]
Multiply both sides by W
[tex]W * \frac{L}{W} = \frac{8}{5} * W[/tex]
[tex]L = \frac{8W}{5}[/tex]
The perimeter of a rectangle:
[tex]Perimeter = 2(L+W)[/tex]
Substitute [tex]L = \frac{8W}{5}[/tex]
[tex]Perimeter = 2(\frac{8W}{5}+W)[/tex]
Take LCM
[tex]Perimeter = 2(\frac{8W + 5W}{5})[/tex]
[tex]Perimeter = 2(\frac{13W}{5})[/tex]
Substitute 117 for Perimeter
[tex]117 = 2(\frac{13W}{5})[/tex]
[tex]117 = \frac{26W}{5}[/tex]
Multiply both sides by [tex]\frac{5}{26}[/tex]
[tex]\frac{5}{26} * 117 = \frac{26W}{5} * \frac{5}{26}[/tex]
[tex]\frac{5 * 117}{26} = W[/tex]
[tex]\frac{585}{26} = W[/tex]
[tex]22.5 = W[/tex]
[tex]W = 22.5[/tex]
Recall that
[tex]L = \frac{8W}{5}[/tex]
[tex]L = \frac{8 * 22.5}{5}[/tex]
[tex]L = \frac{180}{5}[/tex]
[tex]L = 36[/tex]
The diagonal of a rectangle is calculated using Pythagoras theorem as thus;
[tex]D = \sqrt{L^2 + W^2}[/tex]
Substitute values for L and W
[tex]D = \sqrt{36^2 + 22.5^2}[/tex]
[tex]D = \sqrt{1296 + 506.25}[/tex]
[tex]D = \sqrt{1802.25}[/tex]
[tex]D = \sqrt{1802.25}[/tex]
[tex]D = 42.4529150943[/tex]
[tex]D = 42.5\ inch[/tex] (Approximated)
