中考模拟题

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28?y?x?，?x?5，?由?解得∴C点的坐标为?5， ······························· 3分 6?．33??y?6．?y??2x?16．?11 ·················································· 4分 AB·yC??12?6?36．2228 （2）解：∵点D在l1上且xD?xB?8， ?yD??8??8．33∴S△ABC? ∴D点坐标为?8，．········································································· 5分 8? ·

??2xE?16?8．?xE?4．又∵点E在l2上且yE?yD?8，

∴E点坐标为?4，．········································································· 6分 8? ·∴OE?8?4?4，EF?8． ································································ 8分

（3）解法一：①当0≤t?3时，如图1，矩形DEFG与△ABC重叠部分为五边形

．过C作CM?AB于M，CHFGR（t?0时，为四边形CHFG）

则Rt△RGB∽Rt△CMB．

yE l2 C D R yl1E l2 D C R yl1E D l2 C l1R A F O G M （图2）

B x F A G O M B x （图3）

A O F M G B x （图1）

∴

BGRGtRG即?∴RG?2t． ?，，BMCM36 QRt△AFH∽Rt△AMC，112∴S?S△ABC?S△BRG?S△AFH?36??t?2t??8?t???8?t?．

223421644t?．即S??t? ·························································· 14分

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