using the addition or subtraction formulas for sine or cosine.... sinasinb=(cos(a-b)-cos(a+b))/2

Answer:The answer w'll be obtained using formulas cos(a+b) = cosacosb - sinasinbcos(a-b) = cosacosb + sinasinbStep-by-step explanation:Using the trigonometric formula of addition and subtraction of cosine cos(a+b) = cosacosb - sinasinbcos(a-b) = cosacosb + sinasinbw'll get the desired answer.To be solveL.H.S = R.H.Ssinasinb = (cos(a-b)-cos(a+b)/2as we know that cos(a+b) = cosacosb - sinasinbsinasinb = (cos(a-b) - (cosacosb -sinasinb))/2as we know that cos(a-b) = cosacosb + sinasinbsinasinb = ((cosacosb + sinasinb) - (cosacosb -sinasinb))/2sinasinb = (cosacosb + sinasinb - cosacosb + sinasinb)/2sinasinb = (2sinasinb)/2sinasinb = sinasinbhence L.H.S = R.H.S