Find the derivative of the following function at the indicated point: `2cosx"\ "a t"\ "x="\ "pi/2`

Explanation

We have given the function `2cosx` ,

Then `f(x)=2cosx`

Now by derivative formula,

`f'(a)=lim(h->0)(f(a+h)-f(a))/h`

`f'(a)=lim(h->0)(2cos(a+h)-2cos(a))/h`

At `x=pi/2`

`f'((pi)/2)=lim(h->0)(2cos((pi)/2+h)-2cos((pi)/2))/h`

`f'((pi)/2)=lim(h->0)(-2sinh)/h`

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