f(x)=x+π/20sinx.cosyf(y)dy

f(x)=?

The function f(x), that satisfies the condition f(x)=x+π/20sinx.cosyf(y)dy is:

(A) x+23(π2)sinx
(B) x+(π+2)sinx
(C) x+π2sinx
(D) x+(π2)sinx

Solution

We have, f(x)=x+π/20sinx.cosyf(y)dy=x+sinxπ/20cosyf(y)dy=x+sinx.k

Where, k=π/20cosyf(y)dy=π/20cosy(y+siny.k)dy

k=π/20ycosydy+kπ/20cosysinydy

k=ysiny|π/20π/20sinydy+k2π/20sin2ydy=π2+cosy|π/20k2.12cos2y|π/20

k=π21k4(11)=π21+k2

k2=π21=π22

k=π2

Now, f(x)=x+sinx.k=x+(π2)sinx

Answer: (D)

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