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# c4 integration help please. watch

1. How do i integrate:

2sin3xsin2x

solomon paper A, i dont understand how they get to here??

2sin3xsin2x = cosx - cos5x

thanks
2. (Original post by amzy2)
How do i integrate:

2sin3xsin2x

solomon paper A, i dont understand how they get to here??

2sin3xsin2x = cosx - cos5x

thanks
need to use the factor formulae for trignometry
factor formulae
3. What is the expansion of cos (3x - 2x ) and the expansion of cos (3x + 2x)
4. cos(3x+2x) = cos3xcos2x - sin3xsin2x
cos(3x-2x) = cos3xcos2x + sin3xsin2x
5. (Original post by rbnphlp)
need to use the factor formulae for trignometry
factor formulae
thanks - are we meant to know a few patterns like these? i was just know the double angle ones from c3 trig... :/
6. (Original post by amzy2)
thanks - are we meant to know a few patterns like these? i was just know the double angle ones from c3 trig... :/
I think its already given in the formulae booklet page 8
8. (Original post by rbnphlp)
I think its already given in the formulae booklet page 8
I don't think I've ever used those lower 4 formulas in a question before
9. (Original post by HitTheSwitch)
I don't think I've ever used those lower 4 formulas in a question before
With the A* system introduced , trust me they will come in handy
10. (Original post by rbnphlp)
With the A* system introduced , trust me they will come in handy
Oh great!

Cheers, I'll keep an eye out for those types then...
11. (Original post by rbnphlp)
I think its already given in the formulae booklet page 8
o right - yea i dont think i have ever used them either - this was from a solomon...tomorrow ......
12. (Original post by rbnphlp)
With the A* system introduced , trust me they will come in handy
how come i didnt know. A* in EDEXCEL? is it unit wise or subject wise? what about other subjects?
13. (Original post by obviouslystudying)
how come i didnt know. A* in EDEXCEL? is it unit wise or subject wise? what about other subjects?
For all (nearly) subjects and all boards, to get an A* you have to get an average of 90% on the A2 modules as well as an average of 80% over all the modules.

For Maths it is just C3 and C4 where you have to get an average of 90%. For Further Maths you have to get an average of 90% on your best three A2 modules as well as an average of 80% overall.

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