圖形的平移第二課時(shí)課件

北師大?八年級(jí)《數(shù)學(xué)(下)》圖形的平移第三章圖形的平移與旋轉(zhuǎn)北師大?八年級(jí)《數(shù)學(xué)(下)》1123456780–1–2–3–4–512349105在直角坐標(biāo)系中描出以下各點(diǎn)：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)并用線段依次連接，看一看是什么圖案。 yx123456780–1–2–3–4–512349105在直角123456780–1–2–3–4–512349105圖中的魚是將坐標(biāo)為：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的點(diǎn)用線段依次連接而成的，將這條“魚”向右平移5個(gè)單位長(zhǎng)度（1）畫出平移后的新“魚”。在圖中盡量多選取幾組對(duì)應(yīng)點(diǎn)，并將它們的坐標(biāo)填入下表（2）對(duì)應(yīng)點(diǎn)的坐標(biāo)有什么變化？yx縱坐標(biāo)不變，橫坐標(biāo)加5(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x+5,y)(5,0)(10,4)(8,0)(10,1)(10,-1)(8,0)(9,-2)(5,0)123456780–1–2–3–4–512349105圖中的-2-1012345-3–1–2–3–4–51234675如果將原來(lái)的“魚”向左平移4個(gè)單位長(zhǎng)度呢？對(duì)應(yīng)點(diǎn)的坐標(biāo)有什么變化？坐標(biāo)變化為：yx-4猜一猜縱坐標(biāo)保持不變，橫坐標(biāo)減4(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x-4,y)(-4,0)(1,4)(-1,0)(1,1)(1,-1)(-1,0)(0,-2)(-4,0)-2-1012345-3–1–2–3–4–51234675如123456780–1–2–3–4612345如果將原來(lái)的“魚”向上平移3個(gè)單位長(zhǎng)度，對(duì)應(yīng)點(diǎn)的坐標(biāo)有什么變化？yx猜一猜橫坐標(biāo)保持不變，縱坐標(biāo)加3123456780–1–2–3–4612345如果將原來(lái)的“123456780–1–2–3–4–512345如果原圖形向下平移2個(gè)單位長(zhǎng)度，對(duì)應(yīng)點(diǎn)的坐標(biāo)有什么變化？yx猜一猜橫坐標(biāo)保持不變，縱坐標(biāo)減2123456780–1–2–3–4–512345如果原圖形向1、一個(gè)圖形沿x軸方向平移a（a>0）個(gè)單位長(zhǎng)度:(x,y)(x+a,y)2、一個(gè)圖形沿y軸方向平移a（a>0）個(gè)單位長(zhǎng)度:向右平移a個(gè)單位向左平移a個(gè)單位(x-a,y)(x,y)(x,y+a)向上平移a個(gè)單位向下平移a個(gè)單位(x,y-a)小結(jié):平移1、一個(gè)圖形沿x軸方向平移a（a>0）個(gè)單位長(zhǎng)度:(x1.(x,y)(x,y＋4)2.(x,y)(x,y－2)4.(x,y)(3+x,y)3.(x,y)(x-1,y)在坐標(biāo)系中，將坐標(biāo)作如下變化時(shí)，圖形將怎樣變化？