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# C4 Trig. Integration Question watch

1. This question (Q64) is from the review exercise in the Edexcel textbook.

I managed to do part (a) fine and got (xsin2x)/2 + (cos2x)/4 + c as the answer.

How do you do part b?

2. (Original post by jasminetwine)
This question (Q64) is from the review exercise in the Edexcel textbook.

I managed to do part (a) fine and got (xsin2x)/2 + (cos2x)/4 + c as the answer.

How do you do part b?

Use the hint they give you !
3. (Original post by jasminetwine)
This question (Q64) is from the review exercise in the Edexcel textbook.

I managed to do part (a) fine and got (xsin2x)/2 + (cos2x)/4 + c as the answer.

How do you do part b?

You can write you integral as by re-arranging the given identity. This should now be easy to integrate using the answer for your first part.
4. (Original post by Zacken)
You can write you integral as by re-arranging the given identity. This should now be easy to integrate using the answer for your first part.
Second that. Dismantle to give ; by inspection the first integral is pretty much about retrieving your answer from part (a) (do remember to multiply by 1/2 though), while the second integral is something super fundamental.

Hope this clarifies. Peace.
5. Thanks for your help so far guys!

I can see that cos^2(x) = (cos2x+1)/2, using the identity they gave!

Where do you go from there (i.e. How do you 'dismantle' it)?

Thanks
6. Darling I just demonstrated this in my earlier post. Break up the original integral into two parts. Peace.
7. (Original post by WhiteGroupMaths)
Second that. Dismantle to give ; by inspection the first integral is pretty much about retrieving your answer from part (a) (do remember to multiply by 1/2 though), while the second integral is something super fundamental.

Hope this clarifies. Peace.
Is this correct?
8. Perfectly done.

Ouch my neck.

Peace.
9. (Original post by WhiteGroupMaths)
Perfectly done.

Ouch my neck.

Peace.
Thank you so so much!

Have a lovely weekend
10. You too darling. God bless.

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