Question

If f(x) = cosx + sinx then dy/dx at x= 2pie/3 is

Answer 1

f(x) = sinx + cosx
differentiate with respect to x
df(x)/dx = cosx - sinx
dy/dx at x = 2π/3

dy/dx = cos2π/3 - sin2π/3
= cos120° - sin120°
= -1/2 - √3/2
= - (1 + √3)/2

Answer 2

Hey there !!!!!!

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f(x) = cosx+sinx

Differentiating wrt to "x"

dy/dx = -sinx+cosx

dy/dx = cosx-sinx

At x= 2π/3

        = cos2π/3-sin2π/3

          = cos120-sin120

          = -1/2-√3/2

           =-(1+√3)/2 = -(1+1.7)/2 =-2.7/2 = -1.35

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Hope this helped you..............