" D-2.If "x+y+z=(pi)/(2)" show that,"sin2x+sin2y+sin2z=4cos x" cosy cosz."

If x+y+z= (pi)/(2) show that sin 2x + sin 2y + sin 2z =4 cos x cosy cos z

If x + y = pi + z, then prove that sin ^ (2) x + sin ^ (2) y-sin ^ (2) z = 2sin x sin y cos z

If cosx + cosy + cosz = 0 "and" sinx + siny + sinz =0, "then show that" cos (x-y) + cos(y - z) + cos(z - x) = - 3/2.

If sinx+siny+sinz=cosx+cosy+cosz=0, then (A) sin2x+sin2y+sin2z=0 (B) cos2x+cos2y+cos2z=0 (C) tanx+tany+tanz=0 (D) none of these

If x+y+z= pi/2 , prove that : cos(x-y-z) + cos(y-z-x) + cos (z-x-y)-4cosx cosy cosz=0

If x+y+z= pi/2 , prove that : cos(x-y-z) + cos(y-z-x) + cos (z-x-y)-4cosx cosy cosz=0

If cosx + cosy + cosz = 0 and sinx + siny + sinz =0 , then show that cos (x-y) + cos(y - z) + cos(z - x) = - 3/2.