Question

What's the length of d

Answer 1

$d = \sqrt{a^2+b^2+c^2} \ \ \ \ \ \ [a=5, \ b=8, \ c=2] \\ \\ d = \sqrt{5^2+8^2+2^2}= \sqrt{25+64+4}= \sqrt{93} \approx 9.6 \ units$