If Y= mod cosX + mod sinX, then find dy/dX at X= 2pi/3

 At x = 2pi/3 ......cos is -Ve and sinx is +ve. Therefore mod cosx = -cosx and mod sinx=sinx.

therefore Y = -cosX+sinx

dy/dX = sinx+cosx=sin2pi/3+cos2pi/3 =

Considering the value of X at the given point, the function is nothing but f(x) = -cosx+sinx. (From the definition of the modulus function)

Now differentiate and get your result.