Different layout for exercise, header, etc

1. I want to set different layouts in a book, say the bodywidth (4in) + maginalwidth (2in) and 'exercise part' (6in) at the end of each section such as a typical calculus book. I am using `\minipage[h]{6in}` for the 'exercise part' right now, which is not good when a part of 'exercise' needs to be carried over to the next page.

2. I want the header (and footer) width to be 6in, even the bodywidth is 4in. Is anyway to do that??

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You are missing the 'exercises' tag – leo Oct 23 '11 at 4:17

You can use the `package` geometry with the command `\newgeometry`. For more details see the documentation.
The OP mentions `minipage`s and carrying over text parts to the next page, so it seems he/she wants to change the "margins" for parts of a page. For this, the `geometry` package is not appropriate. – lockstep Jan 27 '12 at 20:58
To change the "margins" (better: the indentation) for text blocks in the middle of a page, use the changepage package, the fullwidth package or the `addmargin` environment of the KOMA-Script classes resp. the `scrextend` package which is included in `KOMA-Script`.