Differentiate the following functions with respect to x:



Now




Using cos2θ = 2cos2θ – 1


y = cos–1(cosθ)


Considering the limits,


–1< x < 1


–1< cos2θ < 1


0 < 2θ < π



Now, y = cos–1(cosθ)


y = θ



Differentiating w.r.t x, we get



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