Mister Exam

Derivative of cos²5x/sin²5x

Function f() - derivative -N order at the point
v

The graph:

from to

Piecewise:

The solution

You have entered [src]
   25   
cos  (x)
--------
   25   
sin  (x)
cos25(x)sin25(x)\frac{\cos^{25}{\left(x \right)}}{\sin^{25}{\left(x \right)}}
cos(x)^25/sin(x)^25
Detail solution
  1. 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)=cos25(x)f{\left(x \right)} = \cos^{25}{\left(x \right)} and g(x)=sin25(x)g{\left(x \right)} = \sin^{25}{\left(x \right)}.

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

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

    2. Apply the power rule: u25u^{25} goes to 25u2425 u^{24}

    3. Then, apply the chain rule. Multiply by ddxcos(x)\frac{d}{d x} \cos{\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)}

      The result of the chain rule is:

      25sin(x)cos24(x)- 25 \sin{\left(x \right)} \cos^{24}{\left(x \right)}

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

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

    2. Apply the power rule: u25u^{25} goes to 25u2425 u^{24}

    3. Then, apply the chain rule. Multiply by ddxsin(x)\frac{d}{d x} \sin{\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 of the chain rule is:

      25sin24(x)cos(x)25 \sin^{24}{\left(x \right)} \cos{\left(x \right)}

    Now plug in to the quotient rule:

    25sin26(x)cos24(x)25sin24(x)cos26(x)sin50(x)\frac{- 25 \sin^{26}{\left(x \right)} \cos^{24}{\left(x \right)} - 25 \sin^{24}{\left(x \right)} \cos^{26}{\left(x \right)}}{\sin^{50}{\left(x \right)}}

  2. Now simplify:

    25cos24(x)sin26(x)- \frac{25 \cos^{24}{\left(x \right)}}{\sin^{26}{\left(x \right)}}


The answer is:

25cos24(x)sin26(x)- \frac{25 \cos^{24}{\left(x \right)}}{\sin^{26}{\left(x \right)}}

The graph
02468-8-6-4-2-1010-2e531e53
The first derivative [src]
        26            24          
  25*cos  (x)   25*cos  (x)*sin(x)
- ----------- - ------------------
       26               25        
    sin  (x)         sin  (x)     
25sin(x)cos24(x)sin25(x)25cos26(x)sin26(x)- \frac{25 \sin{\left(x \right)} \cos^{24}{\left(x \right)}}{\sin^{25}{\left(x \right)}} - \frac{25 \cos^{26}{\left(x \right)}}{\sin^{26}{\left(x \right)}}
The second derivative [src]
            /                                  /          2   \\
      23    |      2            2         2    |    26*cos (x)||
25*cos  (x)*|24*sin (x) + 49*cos (x) + cos (x)*|1 + ----------||
            |                                  |        2     ||
            \                                  \     sin (x)  //
----------------------------------------------------------------
                               25                               
                            sin  (x)                            
25((1+26cos2(x)sin2(x))cos2(x)+24sin2(x)+49cos2(x))cos23(x)sin25(x)\frac{25 \left(\left(1 + \frac{26 \cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}}\right) \cos^{2}{\left(x \right)} + 24 \sin^{2}{\left(x \right)} + 49 \cos^{2}{\left(x \right)}\right) \cos^{23}{\left(x \right)}}{\sin^{25}{\left(x \right)}}
The third derivative [src]
             /                                                                   /            2   \                                      \
             |                                                              4    |     702*cos (x)|                                      |
             |                                                           cos (x)*|77 + -----------|                                      |
             |                                        /          2   \           |          2     |         2    /     2            2   \|
       22    |        2             2            2    |    26*cos (x)|           \       sin (x)  /   75*cos (x)*\- cos (x) + 24*sin (x)/|
-25*cos  (x)*|- 73*cos (x) + 552*sin (x) + 75*cos (x)*|1 + ----------| + -------------------------- + -----------------------------------|
             |                                        |        2     |               2                                 2                 |
             \                                        \     sin (x)  /            sin (x)                           sin (x)              /
------------------------------------------------------------------------------------------------------------------------------------------
                                                                    24                                                                    
                                                                 sin  (x)                                                                 
25(75(1+26cos2(x)sin2(x))cos2(x)+(77+702cos2(x)sin2(x))cos4(x)sin2(x)+75(24sin2(x)cos2(x))cos2(x)sin2(x)+552sin2(x)73cos2(x))cos22(x)sin24(x)- \frac{25 \left(75 \left(1 + \frac{26 \cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}}\right) \cos^{2}{\left(x \right)} + \frac{\left(77 + \frac{702 \cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}}\right) \cos^{4}{\left(x \right)}}{\sin^{2}{\left(x \right)}} + \frac{75 \left(24 \sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) \cos^{2}{\left(x \right)}}{\sin^{2}{\left(x \right)}} + 552 \sin^{2}{\left(x \right)} - 73 \cos^{2}{\left(x \right)}\right) \cos^{22}{\left(x \right)}}{\sin^{24}{\left(x \right)}}