- #1

- 86

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i attempted using integrals by parts.. wat i got when i differentiate it i didn't go back to the same integral equation.

is it that it is not possible??

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- Thread starter evra
- Start date

- #1

- 86

- 0

i attempted using integrals by parts.. wat i got when i differentiate it i didn't go back to the same integral equation.

is it that it is not possible??

- #2

gb7nash

Homework Helper

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i want someone to help me with the integral of cosX^2

I'm not sure what you mean here. If you want to take the integral of [tex]\cos x^2[/tex], then this cannot be solved through ordinary methods. However, if you want to solve (cosx)^2, just apply the half-angle formula.

Last edited:

- #3

tiny-tim

Science Advisor

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i attempted using integrals by parts.. wat i got when i differentiate it i didn't go back to the same integral equation.

is it that it is not possible??

∫ cosx.cosx dx

= [sinx.cosx] + ∫sinx.sinx dx

= [sinx.cosx] + ∫ 1 dx - ∫cosx.cosx dx

= [sinx.cosx] + ∫ 1 dx - ∫cosx.cosx dx

so 2∫ cosx.cosx dx = [sinx.cosx] + ∫ 1 dx

(or just use one of the standard trignonometric identites as

- #4

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mr gb7nash, yes i mean ∫cos x^2. but the relation u used above can't work. i tried it but the rsult i got when i defferentiate it i can't come back to the original answer.

please check it.

- #5

tiny-tim

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i tried it but the rsult i got when i defferentiate it i can't come back to the original answer.

please check it.

nooo …

- #6

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i got sinX^2 and when I differentiate this I got 2XcosX^2

- #7

tiny-tim

Science Advisor

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i got sinX^2 and when I differentiate this I got 2XcosX^2

(try using the X

no, if you want to find ∫ cos(x

integration by parts, or the half-angle formula, will only work for ∫ cos

- #8

- 86

- 0

then its not possible.... thanks!! its like sinX^2.

BUT why is it that its not possible.. what are the prooves? a younger brother is bordering me with it and he said i should give him concret mathematical proves.

thanks

- #9

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BUT why is it that its not possible.. what are the prooves? a younger brother is bordering me with it and he said i should give him concret mathematical proves.

thanks

It's possible with an infinite series expansion of sin(A), A=x^2

- #10

- 86

- 0

no i don't think so because i did that and if i defferentiate the answer i got, i can't get back to sin(x2)

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