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# C3 Trigonometry watch

1. Need some help for this trig.

Thanks.
2. (Original post by uer23)
Need some help for this trig.

Thanks.
The second equality should help.

3. (Original post by steve2005)
The second equality should help.

The second ones got a minus in front.
4. (Original post by uer23)
The second ones got a minus in front.
Multiply by minus one.
5. The only formula that I can see (which might work that is) is 2sinAsinB = -[cos(A+B)] - cos(A-B)

Will give it a go and see what comes out.

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Updated: January 15, 2010
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