Please see the attached image.
I need to prove a conditional identity cosA + cosB + cosC = 1 + 4sin(A/2) + sin(B/2) + sin(C/2)
given that A+B+C=pi. But the negative sign at the last is giving me trouble.
Please see the attached image.
I need to prove a conditional identity cosA + cosB + cosC = 1 + 4sin(A/2) + sin(B/2) + sin(C/2)
given that A+B+C=pi. But the negative sign at the last is giving me trouble.