Jacob is building a rectangular prism for a class project. He needs to cover the entire prism in aluminum foil. The length of the prism
is 8 centimeters, the width is 6.5 centimeters, and the height is 3
centimeters. How much aluminum foil will Jacob need for his
project?

Surface area of a rectangular prism is the sum area of the six sides.

A=2(xy+xz+yz)

A=2(8(6.5)+8(3)+6.5(3))

A=2(52+24+19.5)

A=2(95.5)

A=191 cm^2

geometry: triangles

solvers

lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584

irrational, cannot