Maximizing the volume of a trough
A trough is to be made to the dimensions shown, 20 feet long with bottom plank 1 foot wide and side planks 1 foot wide. Cross sections perpendicular to the base of the trough are isosceles trapezoids with shorter base and both legs having a length of 1 foot. Only the angle can be varied (though use of the slider.)
What value of appears to maximize the volume of such a trough?
Developed for use with Thomas' Calculus, published by Pearson.