.
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
333
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中考模拟题
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