Mister Exam

Derivative of sin(y)*cos(y)

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

from to

Piecewise:

The solution

You have entered [src]
sin(y)*cos(y)
sin(y)cos(y)\sin{\left(y \right)} \cos{\left(y \right)}
d                
--(sin(y)*cos(y))
dy               
ddysin(y)cos(y)\frac{d}{d y} \sin{\left(y \right)} \cos{\left(y \right)}
Detail solution
  1. Apply the product rule:

    ddyf(y)g(y)=f(y)ddyg(y)+g(y)ddyf(y)\frac{d}{d y} f{\left(y \right)} g{\left(y \right)} = f{\left(y \right)} \frac{d}{d y} g{\left(y \right)} + g{\left(y \right)} \frac{d}{d y} f{\left(y \right)}

    f(y)=sin(y)f{\left(y \right)} = \sin{\left(y \right)}; to find ddyf(y)\frac{d}{d y} f{\left(y \right)}:

    1. The derivative of sine is cosine:

      ddysin(y)=cos(y)\frac{d}{d y} \sin{\left(y \right)} = \cos{\left(y \right)}

    g(y)=cos(y)g{\left(y \right)} = \cos{\left(y \right)}; to find ddyg(y)\frac{d}{d y} g{\left(y \right)}:

    1. The derivative of cosine is negative sine:

      ddycos(y)=sin(y)\frac{d}{d y} \cos{\left(y \right)} = - \sin{\left(y \right)}

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

  2. Now simplify:

    cos(2y)\cos{\left(2 y \right)}


The answer is:

cos(2y)\cos{\left(2 y \right)}

The graph
02468-8-6-4-2-10102-2
The first derivative [src]
   2         2   
cos (y) - sin (y)
sin2(y)+cos2(y)- \sin^{2}{\left(y \right)} + \cos^{2}{\left(y \right)}
The second derivative [src]
-4*cos(y)*sin(y)
4sin(y)cos(y)- 4 \sin{\left(y \right)} \cos{\left(y \right)}
The third derivative [src]
  /   2         2   \
4*\sin (y) - cos (y)/
4(sin2(y)cos2(y))4 \left(\sin^{2}{\left(y \right)} - \cos^{2}{\left(y \right)}\right)
The graph
Derivative of sin(y)*cos(y)