HELP: PROVING TRIG IDENTIES

[Auntie Social]

I am in pre-cal, and im having difficulites trying to prove the trig equations.
In the instructions is also states that I can only use one side of the equation.
meaning i cant add subtract or do any kind of opperations to both sides;



1 - cos^2A
---------- = sinA
1+sinA

1+sinA (1 - sin^2A)
--------- . 1 - --------------
1+sinA 1+ sinA



1+sinA -(1 - sin^2A)
--------- -------------
1+sinA


that is about how far i got i found a common denotminator and i expanded cos^2A
im stuck. im not to sure what to do next.

 

[galactus]

Is this what you mean?

\(\displaystyle \L\\\frac{1-cos^{2}(A)}{1+sin(A)}=sin(A)\)


If so, I may be wrong, but I do not beleive this is true.

 

[o_O]

Hmm ... I don't think that identity even works.

 

[morson]

You're probably stumped because the identity's not even true, not unless A is an intengral multiple of pi.