Answer:
Step-by-step explanation:
Remark
The first job is to find the diagonal along the bottom. Pretend that the sides and top do not exist for just a moment.
Givens
It becomes a Pythagorean problem.
a = 12
b = 9
c = ?
Solution
a^2 + b^2 = c^2
144 + 81 = c^2
c^2 = 225
sqrt(c^2) = sqrt(225)
c = 15
Remark
Now you look at the diagram again, a little more closely this time.
The diagonal that you want is from the lower right to the upper closest left.
c = 15
d = 8
e = ?
e^2 = c^2 + d^2
e^2 = 15^2 + 8^2
e^2 = 225 + 64
e^2 = 289
e = 17
The shipping box is large enough
Note
There is one think you can note
You can do this entire problem in one step
a = 12 b = 9 c= 8
a^2 + b^2 + c^2 = diagonal from lower right to upper left^2
12^2 + 9^2 + 8^2 = diagonal^2
144 + 81 + 64 = diagonal ^2
289 = diagonal^2
diagonal = 17 just as it did before.