" 8."x sin2y=y cos2x

Let sin x + sin y = cos x + cos y for all x, y in R . What is tan(x/2 + y/2) equal to?

Prove that (i) 2 cos x cos y=cos (x+y)+cos (x-y) (ii) -2 . sin x sin y=cos (x+y)-cos (x-y) (iii) 2 sin x cos y=sin (x+y)+sin (x-y) (iv) 2 cos x sin y=sin (x+y)-sin (x-y)

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

(sin x - sin y)/( cos x + cos y) = tan ""(x-y)/(2)

(sin x - sin y)/( cos x + cos y) = tan ""(x-y)/(2)

(sin x - sin y)/( cos x + cos y) = tan ""(x-y)/(2)

(sin x - sin y)/( cos x + cos y) = tan ""(x-y)/(2)

(sin x - sin y)/( cos x + cos y) = tan ""(x-y)/(2)

If sin x+sin y=a and cos x+cos y=b, then tan((x+y)/2 ' is equal to

Show that ( sin x + sin y) /( cos x + cos y) = tan ""(x+y)/(2)