Question

Find the width of the rectangular prism when the surface area is 208 square centimeters.

Answer 1

SA=2(lw+wh+lh) This is the formula for finding the surface area of a rectangular prism, where SA is surface area, l is length, w is width, and h is height.

208=2(lw+wh+lh)
104=lw+wh+lh Here, I divided both sides by 2 to get ride of the 2.

Now, I used prime factorization to find out all the prime factors of 104, which are 2, 2, 2, and 13. Since rectangular prisms only have 3 dimensions, I needed to combine two of the prime factors. In this case, I can either combine 2 of the 2s to get 2, 4, and 13 or I can combine 13 with one of the 2s to get 26, 2, and 2.

If my dimensions were 2, 4, and 13...
my surface area would be 172 sq cm.

If my dimensions were 2, 2, and 26...
my surface area would be 208 sq cm.

Hence, the width of the rectangular prism when the surface area is 208 square centimeters can be either 2 or 26.