Integral of sin^3x/cos^4x dx
The solution
Detail solution
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Rewrite the integrand:
cos4(x)sin3(x)=cos4(x)(1−cos2(x))sin(x)
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There are multiple ways to do this integral.
Method #1
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Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫u4u2−1du
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Rewrite the integrand:
u4u2−1=u21−u41
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Integrate term-by-term:
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The integral of un is n+1un+1 when n=−1:
∫u21du=−u1
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The integral of a constant times a function is the constant times the integral of the function:
∫(−u41)du=−∫u41du
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The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
So, the result is: 3u31
The result is: −u1+3u31
Now substitute u back in:
−cos(x)1+3cos3(x)1
Method #2
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Rewrite the integrand:
cos4(x)(1−cos2(x))sin(x)=cos4(x)−sin(x)cos2(x)+sin(x)
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute du:
∫u4u2−1du
-
Rewrite the integrand:
u4u2−1=u21−u41
-
Integrate term-by-term:
-
The integral of un is n+1un+1 when n=−1:
∫u21du=−u1
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u41)du=−∫u41du
-
The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
So, the result is: 3u31
The result is: −u1+3u31
Now substitute u back in:
−cos(x)1+3cos3(x)1
Method #3
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Rewrite the integrand:
cos4(x)(1−cos2(x))sin(x)=−cos2(x)sin(x)+cos4(x)sin(x)
-
Integrate term-by-term:
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−cos2(x)sin(x))dx=−∫cos2(x)sin(x)dx
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u21du
-
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
Now substitute u back in:
cos(x)1
So, the result is: −cos(x)1
-
Let u=cos(x).
Then let du=−sin(x)dx and substitute −du:
∫u41du
-
The integral of a constant times a function is the constant times the integral of the function:
∫(−u41)du=−∫u41du
-
The integral of un is n+1un+1 when n=−1:
∫u41du=−3u31
So, the result is: 3u31
Now substitute u back in:
3cos3(x)1
The result is: −cos(x)1+3cos3(x)1
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Now simplify:
3cos(x)−3+cos2(x)1
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Add the constant of integration:
3cos(x)−3+cos2(x)1+constant
The answer is:
3cos(x)−3+cos2(x)1+constant
The answer (Indefinite)
[src]
/
|
| 3
| sin (x) 1 1
| ------- dx = C - ------ + ---------
| 4 cos(x) 3
| cos (x) 3*cos (x)
|
/
−3cos3x3cos2x−1
The graph
2
2 1 - 3*cos (1)
- + -------------
3 3
3*cos (1)
−cos11+3cos311+32
=
2
2 1 - 3*cos (1)
- + -------------
3 3
3*cos (1)
3cos3(1)−3cos2(1)+1+32
Use the examples entering the upper and lower limits of integration.