A printed page is to have 1 in. margin on all sides. The page should contain 80 sq. in. of type. What dimensions of the page will minimize the area of the page while still meeting the other requirements?

1 answer

wh = 80
a = (w+2)(h+2) = (w+2)(80/w + 2)
= 2w + 84 + 160/w

da/dw = 2 - 160/w^2
da/dw = 0 when w^2 = 80

so, as usual a square is your best bet.