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c4 integration help watch

1. ( 1 + sin x ) ^2 dx
2. (Original post by IShouldBeRevising_)
( 1 + sin x ) ^2 dx
Expand and integrate term by term.

For use the sine double angle formula.
3. Expand the bracket.

There is a standard method you should use to integrate with respect to x. Trawl back through your notes. It is very important and involves a trigonometric identity.
4. (Original post by Mr M)
Expand the bracket.

There is a standard method you should use to integrate with respect to x. Trawl back through your notes. It is very important and involves a trigonometric identity.
Do you get

X - 2COSX + 1/4(2x - sin2x)
5. (Original post by IShouldBeRevising_)
Do you get

X - 2COSX + 1/4(2x - sin2x)
Not quite there's a constant of integration missing, and its good practice to collect like terms.
Also
Spoiler:
Show
cos(x) => +sin(x)
6. (Original post by joostan)
Not quite there's a constant of integration missing, and its good practice to collect like terms.
Also
Spoiler:
Show
cos(x) => +sin(x)

x - 2cosx + 1/4(2x - sin2x) + c
7. (Original post by IShouldBeRevising_)

x - 2cosx + 1/4(2x - sin2x) + c
Correct, though like I said, collecting like terms is good practice.
8. (Original post by joostan)
Correct, though like I said, collecting like terms is good practice.
What would the answer be if you collected like terms?
9. (Original post by IShouldBeRevising_)
What would the answer be if you collected like terms?
3/2x - 2cos(x) - sin(2x)/4 +c
Or if you like:
1/4(6x - 8cos(x) - sin(2x)) +c
10. (Original post by joostan)
3/2x - 2cos(x) - sin(2x)/4 +c
Or if you like:
1/4(6x - 8cos(x) - sin(2x)) +c
Ok thanks for your help I cant seem to get the correct answer the question has the limits pi/4 and 0

I have subbed these in to the answer and im getting completely the wrong answer
11. (Original post by IShouldBeRevising_)
Ok thanks for your help I cant seem to get the correct answer the question has the limits pi/4 and 0

I have subbed these in to the answer and im getting completely the wrong answer
What did you get?
12. (Original post by joostan)
What did you get?
A decimal
13. (Original post by IShouldBeRevising_)
A decimal
1.513883683?
This is integral can be evaluated exactly. . .
14. (Original post by joostan)
1.513883683?
This is integral can be evaluated exactly. . .
Yeah thanks the answer is in exact form.
15. (Original post by IShouldBeRevising_)
Yeah thanks the answer is in exact form.
Do you know the values for cos(0), sin(0), cos(pi/4) and sin(pi/2)?

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