SOLUTION: Find the exact length of the side of a square whose diagonal is 3 feet. This is what I have. x^2 + x^2 = (x + 3)^2 x^2 + 4x + 9 x^2 - 4x - 9 = 0 x= 4 plus/minus sqrt 39 - 9(1

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Question 81780: Find the exact length of the side of a square whose diagonal is 3 feet.
This is what I have.
x^2 + x^2 = (x + 3)^2
x^2 + 4x + 9
x^2 - 4x - 9 = 0
x= 4 plus/minus sqrt 39 - 9(1)(-4)/2(1)
6 + 9 sqrt (2)/2
= 6 + 3 sqrt (2)
Would appreciate any help with this question. Thank you

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Since we know the diagonal is 3 feet we can use Pythagoreans theorem



and replace with 3 and with like this:



Square 3

Combine like terms

Divide both sides by 2

Take the square root of both sides

Reduce
Since a negative length doesn't make sense our only answer is



Check:
Plug in the leg into Pythagoreans theorem



Square each individual term

Add

Reduce

Take the square root of both sides

works. This verifies our answer.

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