`cos(A/2)+cos(B/2)-cos(C/2)=4cos((pi+A)/4)cos((pi+B)/4)cos((pi-c)/4)`

In triangle ABC, prove that cos(A/2)+cos(B/2)+cos(C/2)=4cos(pi-A)/4cos(pi-B)/4cos(pi-C)/4

cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=

In triangle ABC,prove that cos((A)/(2))+cos((B)/(2))+cos((C)/(2))=4(cos(pi-A))/(4)(cos(pi-B))/(4)(cos(pi-C))/(4)

"cos(pi/15)cos((2pi)/15)cos((4pi)/15)cos((8pi)/15)=k

In triangle ABC, prove that cos .(A)/(2)+cos.(B)/(2)+cos. (C)/(2) =4 cos .(pi-A)/(4)cos. (pi-B)/(4) cos.(pi-C)/(4)

If A+B+C=pi , prove that : sin ((B+C)/(2)) + sin ((C+A)/(2)) + sin( (A+B)/(2) )= 4cos ((pi-A)/(4)) cos( (pi-B)/(4)) cos((pi-C)/(4)) .

If A+B-C=3pi,\ t h e n\ sin A+ sin B-sin C is equal to- a. 4sin(A/2)sin(B/2)cos(C/2) b. -4sin(A/2)sin(B/2)cos(C/2) c. \ 4cos(A/2)cos(B/2)cos(C/2) d. -4cos(A/2)cos(B/2)cos(C/2)

If A+B-C=3pi, t h e n sin A+ sin B-sin C is equal to- a.4sin(A/2)sin(B/2)cos(C/2) b. -4sin(A/2)sin(B/2)cos(C/2) c. 4cos(A/2)cos(B/2)cos(C/2) d. -4cos(A/2)cos(B/2)cos(C/2)

If A+B+C=pi , prove that : (sin ((B+C)/(2)) + sin ((C+A)/(2)) + sin( (A+B)/(2) )) equals (4cos ((pi-A)/(4)) cos( (pi-B)/(4)) cos((pi-C)/(4))) .