If `cos^2x+cos^2 2x+cos^2 3x=1` then (a) `x=(2n+1)pi/4,\ n in I` (b) `x=(2n+1)pi/2,\ n in I` (c) `x=npi+-\ pi/6,\ n in I` (d) none of these

If cos^(2)x+cos^(2)2x+cos^(2)3x=1 then x=(2n+1)(pi)/(4),n in Ix=(2n+1)(pi)/(2),n in Ix=n pi+-(pi)/(6),n in I (d) none of these

The general solution of cosxcos6x=-1 is (a) x=(2n+1)pi,n in Z (b) x=2npi,n in Z (c) x=npi,n in Z (d) none of these

If 4\ cos^2theta+sqrt(3)=2(sqrt(3)+1)costheta, then theta is 2npi+-pi/3, n in I (b) 2npi+-pi/4, n in I 2npi+-\ pi/6, n in I (d) none of these

If sin^4 x+cos^4x=sinx.cosx, then x is equal to (A) npi, nepsilon I (B) (6n=1) pi/6, n epsilon I (C) (4n+1) pi/4, n epsilon I (D) none of these

Which of the following is not the general solution of 2^(cos2x)+1=3. 2^(-sin^2 x)? (a) npi,n in Z (b) (n+1/2)pi,n in Z (c) (n-1/2)pi,n in Z (d) none of these

Which of the following is not the general solution of 2^(cos2x)+1=3. 2^(-sin^2 x)? (a) npi,n in Z (b) (n+1/2)pi,n in Z (c) (n-1/2)pi,n in Z (d) none of these

The general solution of cos x cos6x=-1 is x=(2n+1)pi,n in Zx=2n pi,quad n in Zx=n pi,n in Z(d) none of these

If cos2x-3cosx+1=(cos e c\ x)/(cotx-cot2x),\ then which of the following is true ? x=(2n+1)\ pi/2,\ n\ in I (b) x=2npi,\ n in I x=2npi+-cos^(-1)(2/5),\ n in I (d) no real x

The general solution of the equation sin^(100)x-cos^(100)x=1 is (a) 2npi+pi/3,n in I (b) n pi+pi/2,n in I (c) npi+pi/4,n in I (d) 2npi=pi/3,n in I

The general solution of the equation 2^(cos2x)=1=3.2^(-sin^2x) is (A) n pi,n epsilon i (B) (n+1/2) pi, n epsilon I (C) (n- 1/2) pi, n epsilon I (D) none of these