Mister Exam

Derivative of cosx*sinx*tgx

Function f() - derivative -N order at the point
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The graph:

from to

Piecewise:

The solution

You have entered [src]
cos(x)*sin(x)*tan(x)
sin(x)cos(x)tan(x)\sin{\left(x \right)} \cos{\left(x \right)} \tan{\left(x \right)}
(cos(x)*sin(x))*tan(x)
Detail solution
  1. Apply the product rule:

    ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)\frac{d}{d x} f{\left(x \right)} g{\left(x \right)} = f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}

    f(x)=sin(x)cos(x)f{\left(x \right)} = \sin{\left(x \right)} \cos{\left(x \right)}; to find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

    1. Apply the product rule:

      ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)\frac{d}{d x} f{\left(x \right)} g{\left(x \right)} = f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}

      f(x)=cos(x)f{\left(x \right)} = \cos{\left(x \right)}; to find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. The derivative of cosine is negative sine:

        ddxcos(x)=sin(x)\frac{d}{d x} \cos{\left(x \right)} = - \sin{\left(x \right)}

      g(x)=sin(x)g{\left(x \right)} = \sin{\left(x \right)}; to find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. The derivative of sine is cosine:

        ddxsin(x)=cos(x)\frac{d}{d x} \sin{\left(x \right)} = \cos{\left(x \right)}

      The result is: sin2(x)+cos2(x)- \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}

    g(x)=tan(x)g{\left(x \right)} = \tan{\left(x \right)}; to find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

    1. Rewrite the function to be differentiated:

      tan(x)=sin(x)cos(x)\tan{\left(x \right)} = \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}}

    2. Apply the quotient rule, which is:

      ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)g2(x)\frac{d}{d x} \frac{f{\left(x \right)}}{g{\left(x \right)}} = \frac{- f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}}{g^{2}{\left(x \right)}}

      f(x)=sin(x)f{\left(x \right)} = \sin{\left(x \right)} and g(x)=cos(x)g{\left(x \right)} = \cos{\left(x \right)}.

      To find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. The derivative of sine is cosine:

        ddxsin(x)=cos(x)\frac{d}{d x} \sin{\left(x \right)} = \cos{\left(x \right)}

      To find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. The derivative of cosine is negative sine:

        ddxcos(x)=sin(x)\frac{d}{d x} \cos{\left(x \right)} = - \sin{\left(x \right)}

      Now plug in to the quotient rule:

      sin2(x)+cos2(x)cos2(x)\frac{\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}}{\cos^{2}{\left(x \right)}}

    The result is: (sin2(x)+cos2(x))tan(x)+(sin2(x)+cos2(x))sin(x)cos(x)\left(- \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \tan{\left(x \right)} + \frac{\left(\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \sin{\left(x \right)}}{\cos{\left(x \right)}}

  2. Now simplify:

    sin(2x)\sin{\left(2 x \right)}


The answer is:

sin(2x)\sin{\left(2 x \right)}

The graph
02468-8-6-4-2-10102-2
The first derivative [src]
/   2         2   \          /       2   \              
\cos (x) - sin (x)/*tan(x) + \1 + tan (x)/*cos(x)*sin(x)
(sin2(x)+cos2(x))tan(x)+(tan2(x)+1)sin(x)cos(x)\left(- \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \tan{\left(x \right)} + \left(\tan^{2}{\left(x \right)} + 1\right) \sin{\left(x \right)} \cos{\left(x \right)}
The second derivative [src]
  /  /       2   \ /   2         2   \                            /       2   \                     \
2*\- \1 + tan (x)/*\sin (x) - cos (x)/ - 2*cos(x)*sin(x)*tan(x) + \1 + tan (x)/*cos(x)*sin(x)*tan(x)/
2((sin2(x)cos2(x))(tan2(x)+1)+(tan2(x)+1)sin(x)cos(x)tan(x)2sin(x)cos(x)tan(x))2 \left(- \left(\sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1\right) + \left(\tan^{2}{\left(x \right)} + 1\right) \sin{\left(x \right)} \cos{\left(x \right)} \tan{\left(x \right)} - 2 \sin{\left(x \right)} \cos{\left(x \right)} \tan{\left(x \right)}\right)
The third derivative [src]
  /  /   2         2   \            /       2   \                   /       2   \ /   2         2   \          /       2   \ /         2   \              \
2*\2*\sin (x) - cos (x)/*tan(x) - 6*\1 + tan (x)/*cos(x)*sin(x) - 3*\1 + tan (x)/*\sin (x) - cos (x)/*tan(x) + \1 + tan (x)/*\1 + 3*tan (x)/*cos(x)*sin(x)/
2(3(sin2(x)cos2(x))(tan2(x)+1)tan(x)+2(sin2(x)cos2(x))tan(x)+(tan2(x)+1)(3tan2(x)+1)sin(x)cos(x)6(tan2(x)+1)sin(x)cos(x))2 \left(- 3 \left(\sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)} + 2 \left(\sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) \tan{\left(x \right)} + \left(\tan^{2}{\left(x \right)} + 1\right) \left(3 \tan^{2}{\left(x \right)} + 1\right) \sin{\left(x \right)} \cos{\left(x \right)} - 6 \left(\tan^{2}{\left(x \right)} + 1\right) \sin{\left(x \right)} \cos{\left(x \right)}\right)