[cos(-A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(A+B+C)],[" sin "500" anno "quad =4cos A cos B cos C]

cos (B+C-A)-cos(C+A-B)+cos(A+B-C)- cos (A+B+C)=

cos(-A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(A+B+C)=4cos A cos B cos C

If A + B + C = 180^(@) prove that: (i) "sin" (B+C-A) + "sin"(C+ A-B) + sin (A + B-C) = 4 sin A sin B sin C (ii) cos(- A+B+C) + cos (A - B + C) + cos (A + B - C) = 1 + 4 cos A cos B cos C (iii) "tan" (B+C - A) + tan (C+A-B) + tan (A + B-C) = tan (B+C - A) tan (C+ A - B) tan (A+B-C)

Prove that: cos(A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(-A+B+C)=4cos A\ cos B\ cos C

Prove that: cos(A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(-A+B+C)=4cos A\ cos B\ cos C

Prove that: cos(A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(-A+B+C)=4cos A cos B cos C

If A + B + C =180^@ , prove that : cos (-A+B +C)+cos(A-B+C)+ cos (A +B-C)=1+ 4cos A cos B cos C .

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