初中數(shù)學(xué)人教八年級(jí)上冊(cè)第十三章軸對(duì)稱時(shí)用坐標(biāo)表示軸對(duì)稱PPT

已知點(diǎn)A(2，－3)B(－1，2)C(－4，－3)關(guān)于x軸的對(duì)稱點(diǎn)關(guān)于y軸的對(duì)稱點(diǎn)關(guān)于原點(diǎn)的對(duì)稱點(diǎn)●A(2，-3)●B(-1，2)●C(-4，-3)歸納：①點(diǎn)(x，y)關(guān)于x軸的對(duì)稱點(diǎn)是

．（橫對(duì)稱，縱變）②點(diǎn)(x，y)關(guān)于y軸的對(duì)稱點(diǎn)是

．（縱對(duì)稱，橫變）③點(diǎn)(x，y)關(guān)于原點(diǎn)的對(duì)稱點(diǎn)是

．（原點(diǎn)對(duì)稱，都變）1．點(diǎn)P(－5，6)關(guān)于x軸的對(duì)稱點(diǎn)的坐標(biāo)為

．2．點(diǎn)P(－5，6)關(guān)于y軸的對(duì)稱點(diǎn)的坐標(biāo)為

．3．點(diǎn)P(－5，6)關(guān)于原點(diǎn)的對(duì)稱點(diǎn)的坐標(biāo)為

．【練習(xí)】(－5，－6)(5，6)(5，－6)知應(yīng)識(shí)用例1已知點(diǎn)A(2a－b，5＋a)，B(2b－1，－a＋b)．(1)若點(diǎn)A，B關(guān)于x軸對(duì)稱，求a，b的值；(2)若A，B關(guān)于y軸對(duì)稱，求a，b的值．(3)若A，B關(guān)于原點(diǎn)對(duì)稱，求a，b的值．8．已知點(diǎn)A(a＋2b，1)，B(－2，2a－b)．(1)若點(diǎn)A，B關(guān)于x軸對(duì)稱，求a，b的值；(2)若點(diǎn)A，B關(guān)于y軸對(duì)稱，求a＋b的值．例2如圖，已知點(diǎn)A(4，－1)，B(2，－4)，C(5，－5)．作出△ABC以x軸為對(duì)稱軸的對(duì)稱圖形△AˊBˊCˊ；（有幾種方法）●A’●B’●C’知應(yīng)識(shí)用10．△ABC在平面直角坐標(biāo)系中的位置如圖所示．A，B，C三點(diǎn)在格點(diǎn)上．(1)畫出△ABC關(guān)于x軸對(duì)稱的△A1B1C1，并寫出點(diǎn)C1的坐標(biāo)；(2)畫出△ABC關(guān)于y軸對(duì)稱的△A2B2C2，并寫出點(diǎn)B2的坐標(biāo)．C1(3，－2)．B2(－1，1)．課小堂結(jié)解題時(shí)緊緊抓住點(diǎn)關(guān)于x軸、y軸和圖形關(guān)于x軸、y軸對(duì)稱的規(guī)律，弄清規(guī)律后就可以輕松解題了．12．若點(diǎn)M(1－2m，m－1)關(guān)