If `tanbeta=2sinalphasingammacos e c(alpha+gamma),` then `cotalpha,cotbeta,cotgamma` are in (a)A.P. (b) G.P. (c) H.P. (d) none of these

If cos2B=(cos(A+C))/("cos"(A-C)) , then tanA ,t a n B ,tanC are in (a)A.P. (b) G.P. (c) H.P. (d) none of these

If sin(y+z-x),sin(z+x-y),"sin"(x+y-z) are in A.P., then t a n x ,tany ,tanz are in (a)A.P. (b) G.P. (c) H.P. (d) none of these

If a , b ,a n dc are in G.P., then a+b ,2b ,a n db+c are in a. A.P b. G.P. c. H.P. d. none of these

If a^2+b^2,a b+b c ,a n db^2+c^2 are in G.P., then a ,b ,c are in a. A.P. b. G.P. c. H.P. d. none of these

If a ,b ,c are in A.P., the a/(b c),1/c ,1/b will be in a. A.P b. G.P. c. H.P. d. none of these

If alpha,beta are the nonzero roots of a x^2+b x+c=0 and alpha^2,beta^2 are the roots of a^2x^2+b^2x+c^2=0 , then a ,b ,c are in (A) G.P. (B) H.P. (C) A.P. (D) none of these

If a x^3+b x^2+c x+d is divisible by a x^2+c ,t h e na ,b ,c ,d are in a. A.P. b. G.P. c. H.P. d. none of these

If in a progression a_1, a_2, a_3, e t cdot,(a_r-a_(r+1)) bears a constant atio with a_rxxa_(r+1) , then the terms of the progression are in a. A.P b. G.P. c. H.P. d. none of these

If x ,y ,z are real and 4x^2+9y^2+16 z^2-6x y-12 y z-8z x=0,t h e nx , y,z are in a. A.P. b. G.P. c. H.P. d. none of these

The value of f(alpha)=sqrt(cos e c^2alpha-2cotalpha)+sqrt(cos e c^2alpha+2cotalpha) can be 2cotalpha (b) -2cotalpha (c) 2 (d) -2