Different answers when I do the same integration

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Nishanth Pradyumna 2022-9-13

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评论： Nishanth Pradyumna 2022-9-13

Hey,

I'm getting different answers when I perform the same integration but by just expanding the squared term.

How is this possible?

As I procced further, I'm getting 2 completely different answers as my result.

Which one is correct?

PS: I'm getting the same answer even after using 'IgnoreAnalyticConstraints',true.

Thanks

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David Hill 2022-9-13

-2ab = -2*cos(n) and is not the same as -2*(1-cos(x))

Nishanth Pradyumna 2022-9-13

@David Hill

My bad. That was a dumb typo. Thanks.

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David Hill 2022-9-13

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They are not the same expressions.

syms x

int((1+cos(x))^2,0,pi)

ans =

int(1+2*cos(x)+cos(x)^2,0,pi)

ans =

int(1+cos(x)^2-2*(1-cos(x)),0,pi)%this is not the same expression

ans =

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Nishanth Pradyumna 2022-9-13

编辑：Nishanth Pradyumna 2022-9-13

My bad, added the wrong screenshot. please try int((1-cos(x))^2,0,pi).

I did not get the same answer with that. (please check the updated screenshot)

Torsten 2022-9-13

在 MATLAB Online 中打开

Look up the binomial formula:

(a-b)^2 = a^2 - 2*a*b + b^2

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