SOLUTION: find the length of the diagonal of a cube with side length of 10cm i don't even know if we learned this!

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Question 199275: find the length of the diagonal of a cube with side length of 10cm
i don't even know if we learned this!
Found 2 solutions by jim_thompson5910, rfer:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,

The trick to this problem is to use the Pythagorean theorem. However, you need to use it twice (since we've moved into 3 dimensions). It's hard to explain why (let alone draw it), so I thought that this would do. Let me know if it makes sense.


It turns out that for a cube with side "x", the length of the diagonal is d=x%2Asqrt%283%29



So in this case, the length of the side is 10 cm. So plug x=10 into d=x%2Asqrt%283%29 to get d=10%2Asqrt%283%29 which approximates to x=17.32


So the length of the diagonal is about 17.32 cm long.

Answer by rfer(16322) About Me  (Show Source):
You can put this solution on YOUR website!
A cube has equal sides, so all sides are 10cm.
pythagorean theorem a^2+b^2=c^2
10^2+10^2=200
square root of 200=14.14cm