Answer:
15.1
Explanation:
To find the length of the rectangular prism' diagonal, use the formula for the length of a diagonal of a right rectangular prism.
d=l2+w2+h2−−−−√
Substitute 7 for l, 6 for w, and 12 for h
Then simplify.
d=72+62+122−−−−√
=49+36+144−−−−√
=229−−−√≈15.1
Therefore, the length of the rectangular prism's diagonal is about 15.1cm.