令∠AOD=∠BOD= θ, ∠ADO=α, 则角BDO= π-α, sin(π-α)=sinα在△AOD中,根据正弦定理:OA/sinα = AD/sinθ, AD = OA*sinθ/sinα=sinθ/sinα类似地,在在△BOD中, OB/sin(π-α) = BD/sinθ, OB/sinα = BD/sinθ,BD = OB*sinθ/sinα=5sinθ/sinα AD : BD = sinθ/sinα : 5sinθ/sinα = 1 : 5