What is the length of the diagonal of a rectangular box with the dimensions of 3cm × 4cm × 12cm?

Answer 1

Your other responder is correct, but let me expand on his answer: You are looking for the internal diagonal of a rectangular solid. This can be obtained by using the Pythagorean theorem twice or what I like to call the Pythagorean theorem on steroids. This is a²+b²+c² = d² where a, b, and c are the given dimensions and d is the length of the interior diagonal.

Best wishes

Answer 2

the length of the diagonal (d) is given by the formula d^2= sum of the squares of the 3 dimensions

d^2= 9+16=144

d^=169

d=13