The value of `Cos^2x + Cos^2y - 2CosxCosyCos(x+y)` is
(A) Sin(x+y)
(B) `Sin^2(x+y)`
(C) `Sin^3(x+y)`
(D) `Sin^4(x+y)`

The value of (sin x cos y + cos x sin y)^2+(cos x cos y -sin x sin y)^2 is equal to

prove that: cos ^ (2) x + cos ^ (2) y-2cos x * cos y * cos (x + y) = sin ^ (2) (x + y)

cos (x + y), sin (x + y), - cos (x + y) sin (xy), cos (xy), sin (xy) sin2x, 0, sin2y] | = sin2 (x + y)

cos x + cos y = (1) / (3), sin x + sin y = (1) / (4) rArr sin (x + y)

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

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

The values of x satisfying the system of equations 2^(sin x-cos y)=1,16^(sin^(2)x+cos^(2)y)=4 are given by :

Solution of differential equation (2x cos y + y ^ (2) cos x) dx (2y sin xx ^ (2) sin y) dx = 0 is (a) x ^ (2) cos y + y ^ (2) sin x = C (b) x cos yy sin x = C (c) x ^ (2) cos ^ (2) y + y ^ (2) sin ^ (2) x = C (d) x cos y + y sin x = C

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

prove that: (sin2x-sin2y)/(cos2y-cos2x)=cot(x+y)