中学生网络课堂本课配套习题挑战模式1/5
单选题
难度系数：
1.
如图，将非等腰△ABC的纸片沿DE折叠后，使点A落在BC边上的点F处. 若点D为AB边的中点，则下列结论：①△BDF是等腰三角形；②∠DFE=∠CFE；③DE是△ABC的中位线，成立的有（ ）
| A: ①② |
| B: ①③ |
| C: ②③ |
| D: ①②③ |
一次做对，真牛！
+5奖励规则>
- 提示1：PHA+5b2i5Y+v55+l4pazREZF5piv4pazQURF5a+55oqY6ICM5oiQ77yM5omA5Lul5Lik5LiJ6KeS5b2i5YWo562J77yM5Y+v5b6XQUQ9REbvvIzogIxE5pivQULkuK3ngrnvvIzmlYXmnIlCRD1ERu+8jOmCo+S5iOKRoOWPr+ivge+8mzwvcD4=
- 提示2：PHA+5Yip55So4oigQURG5piv4pazQkRG55qE5aSW6KeS77yM5Y+v6K+B4oigREZCPeKIoEVERu+8jOmCo+S5iERF4oilQkPvvIzljbNEReaYr+KWs0FCQ+eahOS4reS9jee6v++8jOKRoeW+l+ivge+8mzwvcD4=
- 提示3：PHA+5Yip55SoREXiiKVCQ++8jOS7peWPiuKWs0RGReWSjOKWs0FEReeahOWvueaKmO+8jOWPr+W+l+KIoEVGQz3iiKBFQ0bvvIzljbPilrNFRkPkuZ/mmK/nrYnohbDkuInop5LlvaLvvIzogIziiKBC4omg4oigQ++8jOWNs+KIoERGQu+8jOKIoERGRe+8jOKIoEVGQ++8jOS4jeS8muWQjOaXtuS4ujYwwrDvvIzpgqPkuYjiiKBERkXiiaDiiKBDRkU8L3A+
- 答案：Qg==
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
本课配套习题挑战模式2/5
单选题
难度系数：
2.
矩形ABCD中，R为CD上一定点，P为BC上一动点，E、F分别是AP、RP的中点，当P从B向C移动时，线段EF的长度（）
| A: 逐渐变小 |
| B: 逐渐变大 |
| C: 不变 |
| D: 无法确定 |
一次做对，真牛！
+5奖励规则>
- 提示1：PHA+6L+e5o6lQUPvvJs8L3A+
- 提示2：PHA+RUbmmK/ilrNBUFLnmoTkuK3kvY3nur/vvIzliKnnlKjkuK3kvY3nur/mgKfotKhFRjxpbWcgc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8yMy80MS9yQkFDRTFNTVVYdXpZY3RhQUFBQlNDQjllSW8zNTMucG5nIiBkYXRhLWNrZS1zYXZlZC1zcmM9Imh0dHBzOi8vcDEucWluZ2d1by5jb20vRzEvTTAwLzIzLzQxL3JCQUNFMU1NVVh1elljdGFBQUFCU0NCOWVJbzM1My5wbmciIGhlaWdodD0iNDIiIHdpZHRoPSIyMiI+QVLvvJs8L3A+
- 提示3：PHA+QVLkuLrlr7nop5Lnur/kuI3lj5jvvIzmiYDku6VFRueahOmVv+S5n+S4jeWPmDwvcD4=
- 答案：Qw==
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
本课配套习题挑战模式3/5
单选题
难度系数：
3.
如图，D是△ABC内一点，BD⊥CD，AD=6，BD=4，CD=3，E、F、G、H分别是AB、AC、CD、BD的中点，则四边形EFGH的周长是（ ）
| A: 7 |
| B: 9 |
| C: 10 |
| D: 11 |
一次做对，真牛！
+5奖励规则>
- 提示1：PHA+5qC55o2u5Yu+6IKh5a6a55CG5rGC5Ye6QkPnmoTplb/vvJs8L3A+
- 提示2：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
- 提示3：PHA+5rGC5Ye6RUbjgIFIR+OAgUVI44CBRkfnmoTplb/vvIzku6PlhaXljbPlj6/msYLlh7rlm5vovrnlvaJFRkdI55qE5ZGo6ZW/LjwvcD4=
- 答案：RA==
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
本课配套习题挑战模式4/5
单选题
难度系数：
4.已知第一个三角形的周长为1，它的三条中位线组成第二个三角形，第二个三角形的三条中位线又组成第三个三角形，以此类推，则第2003个三角形的周长为（ ）
A:  |
B:  |
C:  |
D:  |
一次做对，真牛！
+5奖励规则>
- 提示1：IOagueaNruS4ieinkuW9oueahOS4reS9jee6v+WumueQhu+8jOesrOS4gOS4quS4ieinkuW9oueahOWRqOmVv+S4ujHvvJs=
- 提示2：IOaOqOWvvOWHuuesrOS6jOS4quS4ieinkuW9oueahOWRqOmVvzxpbWcgd2lkdGg9OCBoZWlnaHQ9NDIgc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8yMy80MS9yQkFDRTFNTVVZR1FyR0FiQUFBQkRpYTFiZHMxMDAucG5nIj7vvIznrKzkuInkuKrkuInop5LlvaLnmoTlkajplb/kuLo8aW1nIHdpZHRoPTggaGVpZ2h0PTQyIHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvMDAvNTQvckJBQ0ZGTU1VWUd6TlFLbEFBQUJObFNnZHBrODQ1LnBuZyI+
- 提示3：IOeEtuWQjueUseWJjeWHoOS4quS4ieinkuW9oueahOWRqOmVv++8jOWvu+aJvuWRqOmVv+S5i+mXtOeahOinhOW+iw==
- 答案：Qw==
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
本课配套习题挑战模式5/5
单选题
难度系数：
5.
如图，梯形ABCD中，AB∥CD，点E、F、G分别是BD、AC、DC的中点. 已知两底差是6，两腰和是12，则△EFG的周长是（）
| A: 8 |
| B: 9 |
| C: 10 |
| D: 12 |
一次做对，真牛！
+5奖励规则>
- 提示1：PHA+6L+e5o6lQUvvvJs8L3A+
- 提示2：PHA+5qC55o2u5LiJ6KeS5b2i5Lit5L2N57q/5a6a55CG5piT5b6X5omA5rGC55qE5LiJ6KeS5b2i55qE5ZCE6L656ZW/5Li65Y6f5LiJ6KeS5b2i5ZCE6L656ZW/55qE5LiA5Y2K77ybPC9wPg==
- 提示3：PHA+5omA5rGC55qE5LiJ6KeS5b2i55qE5ZGo6ZW/5bCx562J5LqO5Y6f5LiJ6KeS5b2i5ZGo6ZW/55qE5LiA5Y2KPC9wPg==
- 答案：Qg==
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
