sympy/sympy — pull request #1222 by SaurabhJha (2012-04-07 00:15:24+00:00)
Title: This is an improvement to the anamolies present in simplify

I have tried to just import sin and cos and defined tan and cot in terms of sin and cos.
After committing the changes, I tested that and it gave the following responses.
>>trigsimp(tan(x) - 1/cot(x))
0
>>trigsimp(tan(x)**2 - 1/cot(x)**2)
0
I also tried to import just sin and defined cos as ((1-(sin(x))**2))**1/2.....but it gave unxpected results......Maybe some other will attack that problem

-Saurabh Jha