∵a*cosA=b*sinB
∴a/b = sinB/cosA
又∵△ABC中,a/b = sinA/sinB
∴sinB/cosA = sinA/sinB
∴sinAcosA = sinB^2
∴sinAcosA+cosB^2 = sinB^2+cosB^2 = 1
∵a*cosA=b*sinB
∴a/b = sinB/cosA
又∵△ABC中,a/b = sinA/sinB
∴sinB/cosA = sinA/sinB
∴sinAcosA = sinB^2
∴sinAcosA+cosB^2 = sinB^2+cosB^2 = 1