3 exercises

Thaurus said:
If someone could explain how I can slove these exercises.
I was missed the lesson.Sorry for my bad english.
Exercises are here:
http://img31.imageshack.us/img31/4623/mata3.png
Thanks.

The problem (3)

I assume the task is to simplify:

\(\displaystyle \frac{ [1-sin(\alpha)-cos(\alpha)][1-sin(\alpha)+cos(\alpha)]}{sin(\alpha)[sin(\alpha)-1]}\)

\(\displaystyle = \frac{ [1-sin(\alpha)]^2 - cos^2(\alpha)}{sin(\alpha)[sin(\alpha)-1]}\)

\(\displaystyle = \frac{ 1+ sin^2(\alpha) - 2sin(\alpha) - cos^2(\alpha)}{sin(\alpha)[sin(\alpha)-1]}\)

\(\displaystyle = \frac{2sin^2(\alpha) - 2sin(\alpha)}{sin(\alpha)[sin(\alpha)-1]}\)

and continue....
 
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