零加一中:三角形线段比例问题解答 |
送交者: 侠行天涯 2016年12月15日16:15:45 于 [灵机一动] 发送悄悄话 |
三角形线段比例问题解答 ∆RST, U on ST, SU:TU = 2:3. M is midpoint of RU. SM cuts RT on V. RV:VT = ? 解答: Use S(ABC) for ∆ABC area. Because M is midpoint of SV, S(SMU) = S(SMR) and S(VMU) = S(VMR). Because S(SVR) = S(SMR) + S(VMR) and S(SVU) = S(SMU) + S(VMU), S(SVR) = S(SVU). Because SU:TU = 2:3, S(VUS) = S(VUT). S(SVR):S(SVT) = 2:(2+3) = 2:5. |
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