" 47.If "cos(x-y)=-1," then "cos x+cos y=

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

If cos (x-y) =-1, then the values of (cos x+ cos y) and (sin x + sin y) are respectively-

If (sin x) (sin y) = 1, then (cos x) (cos y) =?

If cos x.cos y + sin x.sin y = -1 then cos x + cos y is यदि cos x.cos y + sin x.sin y = -1 हो, तो cos x + cos y का मान क्या होगा?

If cos (x-y)+1=0, then the value of (cos x+ cos y) and (sin x+sin y) is-

If cos (x-y) , cos x , cos (x+y) are three distinct numbers which are in harmonic progression and cos x ne cos y , " then " 1+ cos y =

Given that cos(x-y) +cos (y-z) +cos (z-x)=-3/5 find cos x+ cos y + cos z

I : If cos x + cos y=1/3 , sin x+sin y=1//4 " then " cos (x+y)=7//25 II : If cos x + cos y=1//3 , sin x + sin y=1//4 " then " sin(x+y)=24//25