I'm not in highschool but I did the math I think it's 18
Volume of a Triangle= (b•h•l)/2
(13•10•4)/2
(520)/2
260
V=260
Answer:
h=30cm
Base sides, x=30cm
Step-by-step explanation:
Let x be the dimension of the sides and h the dimension of height;

#Material used is directly proportional to surface area. Minimizing surface area will minimize the amount of material used.

Find area as a function of x:

To minimize Area, we find the first derivative of Area:

#find the second derivative to verify the minimum:

Substitute x in the volume equation to find h:

Hence, the dimensions of the box that minimize the amount of material used h=30cm and x=30cm