# A strip of sheet metal 30 cm wide is to be made into a trough by turning strips up vertically along two sides. How many centimeters should be turned up at east side to obtain the greatest carrying capacity?

##### 1 Answer

Mar 14, 2016

#### Explanation:

Let the 'turn up' be

Then twice the cross sectional area in

#2t*(30-2t) = 60t-4t^2 = 15^2-(4t^2-60t+15^2) = 225-(2t-15)^2#

Now

This minimum value of

Here's a graph of

graph{(225-(2x-15)^2)/20 [-14.83, 25.17, -5.92, 14.08]}