If `cosx+cosy-cos(x+y)=3/2,` then (a)`x+y=0` (b) `x=2y` (c)`x=y` (d) `2x=y`

If cos x+cos y-cos(x+y)=(3)/(2), then (a) x+y=0( b) x=2y( c) x=y( d )2x=y

If (cosx)/(cosy)=2 and cos (x-y)=(sqrt(3))/(2) then tan y=

If cosx+cosy+cosz=sinx+siny+sinz=0" then "cos(x-y)= (a) 0 (b) -1/2 (c) 2 (d) 1

If cosx=3cosy, then 2tan((y-x)/2)=

x=2, y=−1 is a solution of the linear equation (a) x+2y=0 (b) x+2y=4 (c) 2x+y=0 (d) 2x+y=5

If y=2cosx+3sinx-cos2x," then "(d^(2)y)/(dx^(2))+y=

(cos x + cosy)/(cos y -cos x) = cot ((x+y)/(2)) cot ((x-y)/(2))

56.The value of cos^(2)x+cos^(2)y-2cos x cos y cos(x+y) is (A) sin(x+y) (B) sin^(2)(x+y) (C) sin(x+y) (D) sin(x+y)

Equation of the parabola with focus (0,-3) and the directrix y=3 is: (a) x^(2)=-12y (b) x^(2)=12y (c) x^(2)=3y (d) x^(2)=-3y

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