3sinA+4cosB=6 4sinB+3cosA=1....(ii) squaring and adding (i) and (ii) (9sin2A+16cos2B+24sinAcosB)+(16sin2B+9cos2A+24sinBcosA)=37 9(sin2A+cos2A)+16(sin2B+cos2B)+24(sinAcosB+sinBcosA)=37 25+24sin(A+B)=37 24sin(A+B)=12 sin(A+B)=