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# Trig Identities Core 3 watch

1. Hey
please can someone help me with this question because i really can't do it!
'prove the following identity: sec^2x (cos^2x) = cot^2x

thanks
2. Are you sure you've typed it out right? Because last time I checked, (sec² x)(cos² x) = 1 !
3. As nuodai said.

God, he's fast.
4. The guy above is right, looks like you typed it wrong. cot is cos over sine, which i'm sure your aware of
5. (Original post by ghostwalker)
As nuodai said.

God, he's fast.
I reply a lot quicker when I have other stuff (i.e. packing for uni) to do.
6. oh no sorry i haven't aha
it's sec^2 x (cot^2 x - cos^2 x) = cot^2 x
7. (Original post by sophiestanmoor110)
oh no sorry i haven't aha
it's sec^2 x (cot^2 x - cos^2 x) = cot^2 x
Since the LHS is the most complicated, I'd start with that and try and simplify it.

It often helps (as in this case) to put everything into terms of sines and cosines to start with and see what you can do from there.
8. simplify the new expression by expanding the brackets and by using one of the trig identities

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