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The length of the diagonal across the front of the box is 25 inches.
The length of the diagonal across the side of the box is 18. The length of the three-dimensional of the box is 32 inches .
What is the length of the across the top of the box?
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From the condition, you have the system of three equations
= , (1)
= , (2)
= (3)
Add the equations (1) and (2) (both sides). You will get
= (4)
Now distract (3) from (4). You will get
= .
Hence, y = 3 (negative root doesn't fit).
Having this, you easily find = from (1) and then x = 4.
Similarly, you find = from (2) and then z = 3.
Thus yours box has dimensions x = 4, y = 3, z = 3 inches.
Now = = , and = 5 inches.
It is yours diagonal.