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dx/cos^4x

Integral of dx/cos^4x dx

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0111cos4(x)dx\int\limits_{0}^{1} 1 \cdot \frac{1}{\cos^{4}{\left(x \right)}}\, dx
Integral(1/cos(x)^4, (x, 0, 1))
Detail solution
  1. Rewrite the integrand:

    sec4(x)=(tan2(x)+1)sec2(x)\sec^{4}{\left(x \right)} = \left(\tan^{2}{\left(x \right)} + 1\right) \sec^{2}{\left(x \right)}

  2. There are multiple ways to do this integral.

    Method #1

    1. Let u=tan(x)u = \tan{\left(x \right)}.

      Then let du=(tan2(x)+1)dxdu = \left(\tan^{2}{\left(x \right)} + 1\right) dx and substitute dudu:

      (u2+1)du\int \left(u^{2} + 1\right)\, du

      1. Integrate term-by-term:

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          u2du=u33\int u^{2}\, du = \frac{u^{3}}{3}

        1. The integral of a constant is the constant times the variable of integration:

          1du=u\int 1\, du = u

        The result is: u33+u\frac{u^{3}}{3} + u

      Now substitute uu back in:

      tan3(x)3+tan(x)\frac{\tan^{3}{\left(x \right)}}{3} + \tan{\left(x \right)}

    Method #2

    1. Rewrite the integrand:

      (tan2(x)+1)sec2(x)=tan2(x)sec2(x)+sec2(x)\left(\tan^{2}{\left(x \right)} + 1\right) \sec^{2}{\left(x \right)} = \tan^{2}{\left(x \right)} \sec^{2}{\left(x \right)} + \sec^{2}{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=tan(x)u = \tan{\left(x \right)}.

        Then let du=(tan2(x)+1)dxdu = \left(\tan^{2}{\left(x \right)} + 1\right) dx and substitute dudu:

        u2du\int u^{2}\, du

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          u2du=u33\int u^{2}\, du = \frac{u^{3}}{3}

        Now substitute uu back in:

        tan3(x)3\frac{\tan^{3}{\left(x \right)}}{3}

      1. sec2(x)dx=tan(x)\int \sec^{2}{\left(x \right)}\, dx = \tan{\left(x \right)}

      The result is: tan3(x)3+tan(x)\frac{\tan^{3}{\left(x \right)}}{3} + \tan{\left(x \right)}

    Method #3

    1. Rewrite the integrand:

      (tan2(x)+1)sec2(x)=tan2(x)sec2(x)+sec2(x)\left(\tan^{2}{\left(x \right)} + 1\right) \sec^{2}{\left(x \right)} = \tan^{2}{\left(x \right)} \sec^{2}{\left(x \right)} + \sec^{2}{\left(x \right)}

    2. Integrate term-by-term:

      1. Let u=tan(x)u = \tan{\left(x \right)}.

        Then let du=(tan2(x)+1)dxdu = \left(\tan^{2}{\left(x \right)} + 1\right) dx and substitute dudu:

        u2du\int u^{2}\, du

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          u2du=u33\int u^{2}\, du = \frac{u^{3}}{3}

        Now substitute uu back in:

        tan3(x)3\frac{\tan^{3}{\left(x \right)}}{3}

      1. sec2(x)dx=tan(x)\int \sec^{2}{\left(x \right)}\, dx = \tan{\left(x \right)}

      The result is: tan3(x)3+tan(x)\frac{\tan^{3}{\left(x \right)}}{3} + \tan{\left(x \right)}

  3. Add the constant of integration:

    tan3(x)3+tan(x)+constant\frac{\tan^{3}{\left(x \right)}}{3} + \tan{\left(x \right)}+ \mathrm{constant}


The answer is:

tan3(x)3+tan(x)+constant\frac{\tan^{3}{\left(x \right)}}{3} + \tan{\left(x \right)}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                   
 |                       3            
 |      1             tan (x)         
 | 1*------- dx = C + ------- + tan(x)
 |      4                3            
 |   cos (x)                          
 |                                    
/                                     
tan3x3+tanx{{\tan ^3x}\over{3}}+\tan x
The graph
0.001.000.100.200.300.400.500.600.700.800.90020
The answer [src]
  sin(1)    2*sin(1)
--------- + --------
     3      3*cos(1)
3*cos (1)           
tan313+tan1{{\tan ^31}\over{3}}+\tan 1
=
=
  sin(1)    2*sin(1)
--------- + --------
     3      3*cos(1)
3*cos (1)           
2sin(1)3cos(1)+sin(1)3cos3(1)\frac{2 \sin{\left(1 \right)}}{3 \cos{\left(1 \right)}} + \frac{\sin{\left(1 \right)}}{3 \cos^{3}{\left(1 \right)}}
Numerical answer [src]
2.81658164059915
2.81658164059915
The graph
Integral of dx/cos^4x dx

    Use the examples entering the upper and lower limits of integration.