SOLUTION: the perimeter of a square is 36 cm. find the length of the diagonal.

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Question 215356: the perimeter of a square is 36 cm. find the length of the diagonal.
Found 3 solutions by checkley77, drj, MathTherapy:
Answer by checkley77(12844) About Me  (Show Source):
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36/4=8 cm. is the side length
8^2+8^2=d^2
64+64=d^2
128=d^2
d=sqrt128
d=11.3137 cm. is the length of the diagonal.

Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
The perimeter of a square is 36 cm. Find the length of the diagonal.

Step 1. We'll use the Pythagorean Theorem which states that the sum of the square of the sides or legs of a right triangle is equal to the square of the hypotenuse or c%5E2=a%5E2%2Bb%5E2 and for this example, c is the diagonal and a=b is the side since it's a square.

Step 2. So with a=b then c%5E2=a%5E2%2Ba%5E2=2a%5E2 or c=a*sqrt(2) and a=c%2Fsqrt%282%29

Step 3. Perimeter P means that we add up all the form sides or P=4a=4c%2Fsqrt%282%29 or c=P%2Asqrt%282%29%2F4. If P=36, then c=36sqrt%282%29%2F4=9sqrt%282%29 or c=12.73 cm

Step 4. The diagonal is 12.73 cm.

I hope the above steps were helpful.

For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

Good luck in your studies!

Respectfully,
Dr J

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Since the perimeter of the square is 36 cm, then each side = 36%2F4+=+9 cm
By letting diagonal equal D, and using the Pythagorean formula, a%5E2+%2B+b%5E2+=+c%5E2, we get: 9%5E2+%2B+9%5E2+=+D%5E2
D%5E2+=+162 ------- D+=+sqrt%28162%29 = 12.73
Therefore, length of the diagonal, or D = highlight_green%2812.73%29 cm.