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# Trigonometric identities? watch

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1. Im supposed to be using the trigonometic identities:

to solve:
1.
2.

Once again... not a clue where to start(and yes ive read the book, the examples are crap)
1. = 4 and 2. = 1
For number 1, i know that
so
so
But i cant re-arrange the formula to make 1+sinx the subject formula

For number 2 i think i might need to use the 'difference between two squares'

Any help much appreciated, just hints etc
2. What you have done seems wrong, you need to remember (a+b)^2=a^2+2ab+b^2 so expanding e.g. gives .

Expand everything correctly and use c^2+s^2=1 to rearrange it and then factorise into something nice

For question 2 sub cos^2(x)=1-sin^2(x)
3. Thanks!
so, for 1:

Then for 2:
4. yup, you've got 1 correct

I'm not totally sure what your question wants in 2 - multiplying together what you have will leave sin^2(Q) - is that okay?
5. Yea sorry, diddnt finish it off on here
Thats alot +rep
6. An alternative solution to 2 would be to factorise:

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Updated: August 31, 2007
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