Integral of cos^3x/sin^4x dx
The solution
Detail solution
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Rewrite the integrand:
sin4(x)cos3(x)=sin4(x)(1−sin2(x))cos(x)
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There are multiple ways to do this integral.
Method #1
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Let u=sin(x).
Then let du=cos(x)dx and substitute du:
∫u41−u2du
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Rewrite the integrand:
u41−u2=−u21+u41
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Integrate term-by-term:
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u21)du=−∫u21du
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The integral of un is n+1un+1 when n=−1:
∫u21du=−u1
So, the result is: u1
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The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
The result is: u1−3u31
Now substitute u back in:
sin(x)1−3sin3(x)1
Method #2
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Rewrite the integrand:
sin4(x)(1−sin2(x))cos(x)=sin4(x)−sin2(x)cos(x)+cos(x)
-
Let u=sin(x).
Then let du=cos(x)dx and substitute du:
∫u41−u2du
-
Rewrite the integrand:
u41−u2=−u21+u41
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u21)du=−∫u21du
-
The integral of un is n+1un+1 when n=−1:
∫u21du=−u1
So, the result is: u1
-
The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
The result is: u1−3u31
Now substitute u back in:
sin(x)1−3sin3(x)1
Method #3
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Rewrite the integrand:
sin4(x)(1−sin2(x))cos(x)=−sin2(x)cos(x)+sin4(x)cos(x)
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Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−sin2(x)cos(x))dx=−∫sin2(x)cos(x)dx
-
Let u=sin(x).
Then let du=cos(x)dx and substitute du:
∫u21du
-
The integral of un is n+1un+1 when n=−1:
∫u21du=−u1
Now substitute u back in:
−sin(x)1
So, the result is: sin(x)1
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Let u=sin(x).
Then let du=cos(x)dx and substitute du:
∫u41du
-
The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
Now substitute u back in:
−3sin3(x)1
The result is: sin(x)1−3sin3(x)1
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Now simplify:
3sin(x)3−sin2(x)1
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Add the constant of integration:
3sin(x)3−sin2(x)1+constant
The answer is:
3sin(x)3−sin2(x)1+constant
The answer (Indefinite)
[src]
/
|
| 3
| cos (x) 1 1
| ------- dx = C + ------ - ---------
| 4 sin(x) 3
| sin (x) 3*sin (x)
|
/
3sin3x3sin2x−1
The graph
Use the examples entering the upper and lower limits of integration.