Question

On lecture 13, (lecture on lagrange multipliers), An "advanced example" is solved. i think there is an error... while writing the equation for the constraint ( area of the base is a known constant), the lines u1, u2 and u3 are ASSUMED to be perpendicular to each of the given sides, if u1 u2 and u3 were indeed perpendicular, there is only one possibility for the lengths of u1,u2 and u2. thus they are known values and there is no problem to solve, the function that needs to be minimized has no variables in it!!

Answer 1

here's the link to the lecture im talking about

http://ocw.mit.edu/courses/mathematics/18-02sc-multivariable-calculus-fall-2010/2.-partial-derivatives/part-c-lagrange-multipliers-and-constrained-differentials/session-41-advanced-example/