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2013中考數(shù)學(xué)軸對(duì)稱(chēng)圖形模擬試題及答案
例1 (2012?柳州)娜娜有一個(gè)問(wèn)題請(qǐng)教你,下列圖形中對(duì)稱(chēng)軸只有兩條的是( ?。?
A. B. C. D.
圓 等邊三角形 矩形 等腰梯形
考點(diǎn):軸對(duì)稱(chēng)圖形.
分析:根據(jù)軸對(duì)稱(chēng)圖形的概念,分別判斷出四個(gè)圖形的對(duì)稱(chēng)軸的條數(shù)即可.
解答:解:A、圓有無(wú)數(shù)條對(duì)稱(chēng)軸,故本選項(xiàng)錯(cuò)誤;
B、等邊三角形有3條對(duì)稱(chēng)軸,故本選項(xiàng)錯(cuò)誤;
C、矩形有2條對(duì)稱(chēng)軸,故本選項(xiàng)正確;
D、等腰梯形有1條對(duì)稱(chēng)軸,故本選項(xiàng)錯(cuò)誤.
故選C.
點(diǎn)評(píng):本
2、題考查軸對(duì)稱(chēng)圖形的概念,解題關(guān)鍵是能夠根據(jù)軸對(duì)稱(chēng)圖形的概念正確找出各個(gè)圖形的對(duì)稱(chēng)軸的條數(shù),屬于基礎(chǔ)題.
例2 (2012?成都)如圖,在平面直角坐標(biāo)系xOy中,點(diǎn)P(-3,5)關(guān)于y軸的對(duì)稱(chēng)點(diǎn)的坐標(biāo)為( ?。?
A.(-3,-5) B.(3,5) C.(3.-5) D.(5,-3)
考點(diǎn):關(guān)于x軸、y軸對(duì)稱(chēng)的點(diǎn)的坐標(biāo).
分析:根據(jù)關(guān)于y軸對(duì)稱(chēng)的點(diǎn),縱坐標(biāo)相同,橫坐標(biāo)互為相反數(shù)解答.
解答:解:點(diǎn)P(-3,5)關(guān)于y軸的對(duì)稱(chēng)點(diǎn)的坐標(biāo)為(3,5).
故選B.
點(diǎn)評(píng):本題考查了關(guān)于x軸、y軸對(duì)稱(chēng)的點(diǎn)的坐標(biāo),解決本題的關(guān)鍵是掌握好對(duì)稱(chēng)點(diǎn)的坐標(biāo)規(guī)律:
(1)關(guān)于x軸對(duì)稱(chēng)的點(diǎn),橫坐
3、標(biāo)相同,縱坐標(biāo)互為相反數(shù);
(2)關(guān)于y軸對(duì)稱(chēng)的點(diǎn),縱坐標(biāo)相同,橫坐標(biāo)互為相反數(shù);
(3)關(guān)于原點(diǎn)對(duì)稱(chēng)的點(diǎn),橫坐標(biāo)與縱坐標(biāo)都互為相反數(shù).
對(duì)應(yīng)訓(xùn)練
1. (2012?寧波)下列交通標(biāo)志圖案是軸對(duì)稱(chēng)圖形的是( ?。?
A. B. C. D.
考點(diǎn):軸對(duì)稱(chēng)圖形.
專(zhuān)題:常規(guī)題型.
分析:根據(jù)軸對(duì)稱(chēng)圖形的概念對(duì)各選項(xiàng)分析判斷后利用排除法求解.
解答:解:A、不是軸對(duì)稱(chēng)圖形,故本選項(xiàng)錯(cuò)誤;
B、是軸對(duì)稱(chēng)圖形,故本選項(xiàng)正確;
C、不是軸對(duì)稱(chēng)圖形,故本選項(xiàng)錯(cuò)誤;
D、不是軸對(duì)稱(chēng)圖形,故本選項(xiàng)錯(cuò)誤.
故選B.
點(diǎn)評(píng):本題考查了軸對(duì)稱(chēng)圖形,掌握中心對(duì)稱(chēng)圖形與軸對(duì)稱(chēng)圖形的概
4、念:軸對(duì)稱(chēng)圖形的關(guān)鍵是尋找對(duì)稱(chēng)軸,圖形兩部分沿對(duì)稱(chēng)軸折疊后可重合.
2.(2012?沈陽(yáng))在平面直角坐標(biāo)系中,點(diǎn)P(-1,2)關(guān)于x軸的對(duì)稱(chēng)點(diǎn)的坐標(biāo)為( ?。?
A.(-1,-2) B.(1,-2) C.(2,-1) D.(-2,1)
考點(diǎn):關(guān)于x軸、y軸對(duì)稱(chēng)的點(diǎn)的坐標(biāo).
分析:根據(jù)關(guān)于x軸對(duì)稱(chēng)的點(diǎn),橫坐標(biāo)相同,縱坐標(biāo)互為相反數(shù)解答.
解答:解:點(diǎn)P(-1,2)關(guān)于x軸的對(duì)稱(chēng)點(diǎn)的坐標(biāo)為(-1,-2).
故選A.
點(diǎn)評(píng):本題考查了關(guān)于x軸、y軸對(duì)稱(chēng)的點(diǎn)的坐標(biāo),解決本題的關(guān)鍵是掌握好對(duì)稱(chēng)點(diǎn)的坐標(biāo)規(guī)律:
(1)關(guān)于x軸對(duì)稱(chēng)的點(diǎn),橫坐標(biāo)相同,縱坐標(biāo)互為相反數(shù);
(2)關(guān)于y軸對(duì)稱(chēng)的點(diǎn),縱坐標(biāo)相同,橫坐標(biāo)互為相反數(shù);
(3)關(guān)于原點(diǎn)對(duì)稱(chēng)的點(diǎn),橫坐標(biāo)與縱坐標(biāo)都互為相反數(shù).
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