**Optimization**:/

7. A rectangular beam is to be cut from a cylindrical log of diameter 20cm.

The diagram (circle with rectangle inside touching edges) shows a cross-section of the log and beam where the beam has a breadth of w cm and a depth of d cm.

The strength S of the beam is given by

S=1.7w(400-w^2).

Find the dimensions of the beam for maximum strength.

Ans

d=20\/(2/3)

* The \/ is meant to be a square root :/

11. I'm really confused by how to include a restriction on the y-axis ??? Could I add in an equation for a line that is horizontal to the x-axis?

I hope this is clarified well enough, really stuck and terrified about Thurs