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)`

Prove that : (cos x - cos y)^(2) + (sin x - sin y)^(2) = 4 sin^(2) ((x - y)/(2))

Solve: dy/dx = sin(x+y) + cos(x+y)

Solve: dy/dx = sin(x+y) + cos(x+y)

If cos(y-z)+cos(z-x)+cos(x-y)=-3/2, prove that cos x + cos y + cos z = 0 = sin x + siny + sinz.

If sin(x y)+cos(x y)=0 , then (dy)/(dx) is

Prove that : (cos x + cos y)^2 + (sin x - sin y)^2 = 4 cos^2\ (x+y)/2

If 3sin(x y)+4cos(x y)=5 , then (dy)/(dx)= (a) y/x (b) (3sin(x y)+4cos(x y))/(3cos(x y)-4sin(x y)) (c) (3cos(x y)+4sin(x y))/(4cos(x y)-3sin(x y)) (d) none

lf cos x + cosy-cos z = 0 = sin x + sin y + sin z then cos((x-y)/2)=

Find the value of the determinant |"cos"(x-y)"cos"(y-z)"cos"(z-x)"cos"(x+y)"cos"(y+z)cos(z+x)"sin"(x+y)"sin"(y+z)s in(z+x)|

Solve (dy)/(dx)=cos(x+y)-sin(x+y) .