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# C4 trig integration-please help :) watch

1. So I have my C4 exam tomorrow,
was doing solomon paper L,
and came across this trig integration:

integrate: (sin3x)*(cosx)^2
between the limits pi/4 and 0.

Someone please shoe me how to get that trig function looking normal and integratable???
2. ...I have checked out the mark scheme, and it still makes no sense unfortunately.
They manage to get from (sin3x)*(cosx)^2 to 0.25sin4x+0.5sin2x but i dont know how!!!!

3. If use use this and recognition (you should have products of cos powers and sins) you should be able to do it. Ask if you need more help.
4. (Original post by rmod)
So I have my C4 exam tomorrow,
was doing solomon paper L,
and came across this trig integration:

integrate: (sin3x)*(cosx)^2
between the limits pi/4 and 0.

Someone please shoe me how to get that trig function looking normal and integratable???
Which paper, which question?
5. paper L 3b
....this is a bit embarrassing but i made a mistake when copying the qn down to work it out... theres no cosx squared only cosx. probs makes things a bit easier...
6. (Original post by rmod)
paper L 3b
....this is a bit embarrassing but i made a mistake when copying the qn down to work it out... theres no cosx squared only cosx. probs makes things a bit easier...
It doesn't really make it easier - the method is still the same.

Have you made any progress?
7. ummm not really. It's reached that time of night where my brain starts closing down. I'm just gonna hope that one doesnt come up tomorrow/ I'll be sharper tomorrow and able to get it thank you for the help though- i got the bit you showed me, but get stuck when that extra cosx comes into it.
8. Use the SinA SinB= 2Sin(A+B/2)Cos(A_B/2)

Formula to turn the product into a sum.

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