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Use-the-reduction-formular-I-n-sin-n-x-dx-1-n-sin-n-1-x-cos-x-n-1-n-I-n-2-to-evaluate-I-n-sin-6-x-dx-




Question Number 12535 by tawa last updated on 24/Apr/17
Use the reduction formular.  I_n  = ∫sin^n (x) dx = −(1/n) sin^(n − 1) (x)cos(x) + ((n − 1)/n)I_n  − 2 , to evaluate   I_(n ) = ∫sin^6 (x) dx
Usethereductionformular.In=sinn(x)dx=1nsinn1(x)cos(x)+n1nIn2,toevaluateIn=sin6(x)dx
Answered by mrW1 last updated on 25/Apr/17
I_n  = ∫sin^n (x) dx = −(1/n) sin^(n − 1) (x)cos(x) + ((n − 1)/n)I_(n−2)   I_6 =∫sin^6  x dx=−(1/6)sin^5  x cos x+(5/6)∫sin^4  x dx  I_4 =∫sin^4  x dx=−(1/4)sin^3  x cos x+(3/4)∫sin^2  x dx  I_2 =∫sin^2  x dx=−(1/2)sin x cos x+(1/2)∫ dx=(1/2)x−((sin 2x)/4)    I_4 =−(1/4)sin^3  x cos x+(3/4)((1/2)x−((sin 2x)/4))=(3/8)x−(3/(16))sin 2x−(1/4)sin^3 cos x    I_6 =−(1/6)sin^5  x cos x+(5/6)[(3/8)x−(3/(16))sin 2x−(1/4)sin^3 cos x]  =(5/(16))x−(5/(32))sin 2x−(1/(24))sin^3 cos x−(1/6)sin^5  x cos x+C
In=sinn(x)dx=1nsinn1(x)cos(x)+n1nIn2I6=sin6xdx=16sin5xcosx+56sin4xdxI4=sin4xdx=14sin3xcosx+34sin2xdxI2=sin2xdx=12sinxcosx+12dx=12xsin2x4I4=14sin3xcosx+34(12xsin2x4)=38x316sin2x14sin3cosxI6=16sin5xcosx+56[38x316sin2x14sin3cosx]=516x532sin2x124sin3cosx16sin5xcosx+C
Commented by tawa last updated on 25/Apr/17
wow, God bless you sir.
wow,Godblessyousir.

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