3.3軸對(duì)稱與坐標(biāo)變化

3.3軸對(duì)稱與坐標(biāo)變化3.3軸對(duì)稱與坐標(biāo)變化學(xué)習(xí)目標(biāo)1.掌握關(guān)于x軸或y軸對(duì)稱的兩個(gè)

點(diǎn)的坐標(biāo)關(guān)系。2.能在平面直角坐標(biāo)系中畫出一

些簡(jiǎn)單的關(guān)于x軸和y軸的對(duì)稱

圖形1、預(yù)習(xí)課本P68-69頁(yè)的內(nèi)容。2、點(diǎn)的對(duì)稱問題。(1)點(diǎn)A(a,b)關(guān)于x軸的對(duì)稱點(diǎn)是

_______(2)點(diǎn)A(a,b)關(guān)于y軸的對(duì)稱點(diǎn)是

_______自主學(xué)習(xí)探究1：如圖，你能畫出點(diǎn)A關(guān)于x軸的對(duì)稱點(diǎn)嗎?·31425-2-4-1-3012345-4-3-2-1A(2,3)·A′(2,-3)你能說出點(diǎn)A與點(diǎn)A’坐標(biāo)的關(guān)系嗎？畫出下列各點(diǎn)關(guān)于x軸的對(duì)稱點(diǎn)31425-2-4-1-3012345-4-3-2-1B(-4,2)··C(3,-4)·B′(-4,-2)·C′(3,4)思考：關(guān)于x軸對(duì)稱的點(diǎn)的坐標(biāo)具有怎樣的關(guān)系？關(guān)于x軸對(duì)稱的點(diǎn)的坐標(biāo)的特點(diǎn)是:橫坐標(biāo)相等,縱坐標(biāo)互為相反數(shù).1、點(diǎn)P(-5,6)與點(diǎn)Q關(guān)于x軸對(duì)稱，則點(diǎn)Q的坐標(biāo)為________.2、點(diǎn)M(a,-5)與點(diǎn)N(-2,b)關(guān)于x軸對(duì)稱，則a=_____,b=_____.(-5,-6)-25探究2：如圖，畫出點(diǎn)A關(guān)于y軸的對(duì)稱點(diǎn)·31425-2-4-1-3012345-4-3-2-1A(2,3)·A′(-2,3)你能說出點(diǎn)A與點(diǎn)A′坐標(biāo)的關(guān)系嗎？在平面直角坐標(biāo)系中畫出下列各點(diǎn)關(guān)于y軸的對(duì)稱點(diǎn).31425-2-4-1-3012345-4-3-2-1B(-4,2)··C(3,-4)·B′(4,2)·C′(-3,-4)思考：關(guān)于y軸對(duì)稱的點(diǎn)的坐標(biāo)具有怎樣的關(guān)系？關(guān)于y軸對(duì)稱的點(diǎn)的坐標(biāo)的特點(diǎn)是:橫坐標(biāo)互為相反數(shù),縱坐標(biāo)相等.1、點(diǎn)P(-5,6)與點(diǎn)Q關(guān)于y軸對(duì)稱，則點(diǎn)Q的坐標(biāo)為________.2、點(diǎn)M(a,-5)與點(diǎn)N(-2,b)關(guān)于y軸對(duì)稱，則a=_____,b=_____.(5,6)2-5關(guān)于x軸對(duì)稱的點(diǎn)橫坐標(biāo)相等,縱坐標(biāo)互為相反數(shù).

關(guān)于y軸對(duì)稱的點(diǎn)橫坐標(biāo)互為相反數(shù),縱坐標(biāo)相等.點(diǎn)（x,y）關(guān)于x軸對(duì)稱的點(diǎn)的坐標(biāo)為______.點(diǎn)（x,y）關(guān)于y軸對(duì)稱的點(diǎn)的坐標(biāo)為______.(x,-y)(-x,y)例1.點(diǎn)M(-2,1)關(guān)于x軸對(duì)稱的點(diǎn)的坐標(biāo)是（）A(-2,-1)B(2,1)C(2,-1)D(1,-2)2.已知點(diǎn)A(a,3),點(diǎn)B(-2,b)關(guān)于x軸對(duì)稱，那么a=_____b=_____3.已知點(diǎn)P(a,3),點(diǎn)Q(-2,b)關(guān)于y軸對(duì)稱，則a=_____

,b=_______

.A-2

-3

-2

3

△ABC關(guān)于y軸對(duì)稱的圖形△A’B’C’，△ABC關(guān)于x軸對(duì)稱的圖形△A’’B’’C’’如圖所示.點(diǎn)的對(duì)稱問題。(1)點(diǎn)A(a,b)關(guān)于x軸的對(duì)稱點(diǎn)是