tanb=√5/5b属于第一象限时：sinb=√6/6,cosb=√30/6b属于第三象限时:sinb=-√6/6,cosb=-√30/6sina/sinb=sinacosb+cosasinbsina=sinasinbcosb+cosasin^2b1=sinbcosb+cotasin^2bcota=(1-sinbcosb)/sin^2bcota=(1-√5...