Max/Min turning points problems question (1 Viewer)

[Lurking.death]

Q15 from 2U fitzpatrick (P348):
A rectangle PQRS is placed inside a scalene triangle ABC. If the area of ABC is constant, prove that the maximum area of the rectangle is one-half of the area of ABC.

I know the area of triangle is constant so im trying to eliminate some constants in my formula so i can differentiate, but there's still too many. :S

 

[AlvinCY]

I've put my answer onto a PDF... I can't draw diagrams on BoS

Enjoy.

http://www.geocities.com/alvin_cy_mak/answer.pdf

Try that.