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

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

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

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

If (cos x)/(cos y)=a and (sin x)/(sin y)=b, then (a ^(2)-b^(2))*sin^(2)y =......

if x and y are acute angles such that cos x+cos y=(3)/(2) and sin x+sin y=(3)/(4) then sin(x+y)=

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

If tan x=(2b)/(a-c),y=a cos^(2)x+2b sin x cos x+c sin^(2)xz=a sin^(2)x-2b sin x cos x+c cos^(2)x, that y-z=a-c.

lf_ (cos x + cos y-cos z = 0 = sin x + sin y + sin) then cos ((xy) / (2)) =

Prove that :(sin x+sin y)/(cos x+cos y)=tan((x+y)/(2))

If ((sin x)^(2y))/((cos x)^((2)/(2)))+((cos x)^(2y))/((sin x)^((2)/(2)))=sin2x for 0