There exists a simple solution. However, it demands some efforts for conversion your math pdf to another pdf.
1. Download pdflrfwin-0.99.exe from
http://projects.mobileread.com/reade...rfwin-0.99.zip
2. Run pdflrfwin-0.99.exe, browse for your pdf (djvu is ok as well) and set output file extension to zip (do it by hand in corresponding output file box, just replace lrf by zip)
3. In preview you can visually control and set margin crop.
4. Run pdflrfwin, it will create zip file with png images representing snapshots of half pages rotated in landscape position.
5. Open zip file and place all png images in separate folder.
6. Download any free tool capable to merge multiple png into single pdf (say, PDFill from
http://www.pdfill.com/pdf_tools_free.html).
6. Merge all png in single pdf and read this pdf on your Kindle in landscape orientation.
This will work even on Kindle Touch (Touch is unable to turn screen image to landscape orientation) because all pages in resulting pdf are already 90 degrees rotated.
Note that pdflrf tries to cut pages between lines of text. However, in rare ocasions it cuts big formulas lengthwise, that may cause some problems.