If `cos x + cos y + cos alpha = 0 and sin x + sin y + sin alpha = 0` then `cot((x+y)/2)` is

cos x + cos y + cos z = 0 and sin x + sin y + sin z, then cos ^(2) (( x-y)/( 2)) =

cos x + cos y + cos z = 0 and sin x + sin y + sin, then cos ^ (2) ((xy) / (2)) =

If cosx+cosy+cosalpha=0 and sinx+siny+sinalpha=0 then cot((x+y)/2)= ................. A) sin alpha B) cos alpha C) cot alpha D) sin ((x+y)/(2))

If cos x + cos y + cos z =0 = sin + sin y +sin z then tan (x-y) =

If cos(x - y)= -1 , show that cos x + cos y = 0 and sin x + sin y = 0 .

If sin x + sin y> = cos alpha cos x, AA x in R then sin y + cos alpha =

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

If x sin ^3 alpha + y cos^3 alpha = sin alpha cos alpha and x sin alpha - y cos alpha =0 , then x^2 +y^2 is

If sin x + sin y + sin z = 0 and cos x + cos y + cos z = 0 then prove that cot (x+y)/2 = cot z and cos (x-y)/2 = pm 1/2