Question

If x + y = z, then cos^2 x + cos^2 y + cos^2 z – 2 cos x cos y cos z is equal to​

Answer 1

cos^-1 x + cos^-1 y+ cos^-1z=3.pi=pi+pi+pi cos^-1x+cos^-1y +cos^ ... On equating both sides. x=y=z =-1.