If `cosx=3cosy`, then `2tan.(y-x)/(2)` is equal to

If sin x + sin y =(1)/(2) andcosx+cosy=1 , then tan (x+y) is equal to

If cosx-sinalphacotbetasinx=cosalpha,then tan""(x)/(2) is equal to

If cosx=(2cosy-1)/(2-cosy), where x , y in (0,pi) then tan(x/2)cot(y/2) is equal to sqrt(2) (b) sqrt(3) (c) 1/(sqrt(2)) (d) 1/(sqrt(3))

If cosx=(2cosy-1)/(2-cosy), where x , y in (0,pi) then tan(x/2)xxcot(y/2) is equal to (a) sqrt(2) (b) sqrt(3) (c) 1/(sqrt(2)) (d) 1/(sqrt(3))

If cosx=(2cosy-1)/(2-cosy), where x , y in (0,pi) then tan(x/2)xxcot(y/2) is equal to (a) sqrt(2) (b) sqrt(3) (c) 1/(sqrt(2)) (d) 1/(sqrt(3))

If cosx=(2cosy-1)/(2-cosy) , where x,y in(0,pi) , then "tan"(x)/(2)"cot"(y)/(2) is equal to

If sinx+cosy=(1)/(3) and cos x+siny=(3)/(4) , then the value of tan((x-y)/(2)) is equal to

If (cosx)^y=(cosy)^x , find (dy)/(dx)