Q. 7

Write the values of x in [0, π] for which and cos 2x are in A.P.

Answer :

a, a+r, a+2r

so A1+A3=2A2

here sin2x + cos2x = 1

2sin x cos x + 1-2sin2x =1

sin x cos x - sin2x=0

sin x (cos x-sin x)=0

if sin x =0

then x =0, π

if sin x=cos x

then x = π/4

So, all possible values are

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