初二数学《变化的鱼》ppt课件 (2)

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123456780–1–2–3–4–512349105在直角坐标系中描出以下各点:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)并用线段依次连接,看一看是什么图案。yx第3节变化的鱼123456780–1–2–3–4–512349105在直角坐标系中描出以下各点:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)并用线段依次连接,看一看是什么图案.yx图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的纵坐标保持不变,将各坐标的横坐标变成原来的2倍会得到什么?则坐标变化为:原图形被横向拉伸2倍(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(2x,y)(0,0)(10,4)(6,0)(10,1)(10,-1)(6,0)(8,-2)(0,0)123456780–1–2–3–4–512349105图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的纵坐标保持不变,将各坐标的横坐标变成原来的1/2,图形会怎么变?则坐标变化为:yx原图形被横向压缩1/2(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x/2,y)(0,0)(2.5,4)(1.5,0)(2.5,1)(2.5,-1)(1.5,0)(2,-2)(0,0)123456780–1–2–3–4–512349105图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的则坐标变化为纵坐标保持不变,将各坐标的横坐标加2又会怎样?yx原图形被横向(向右)平移2个单位(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x+2,y)(2,0)(7,4)(5,0)(7,1)(7,-1)(5,0)(6,-2)(2,0)123456780–1–2–3–4–512349105图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的则坐标变化为:纵坐标保持不变,将各坐标的横坐标减2,图案会变成什么样?yx-1-2原图形被向左平移2个单位(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x-2,y)(-2,0)(3,4)(1,0)(3,1)(3,-1)(1,0)(2,-2)(-2,0)12345-1-2-30–1–2–3–4–51234-4-55图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的yx想一想与原图形关于y轴对称将各坐标的纵坐标保持不变,横坐标都乘以-1,图形会变成什么样?则坐标变化为(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(-x,y)(0,0)(-5,4)(-3,0)(-5,1)(-5,-1)(-3,0)(-2,-2)(0,0)–4123456780–1–2–361234578910xy图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的如果横坐标保持不变,纵坐标变成原来的2倍,那么所得图案又会发生什么变化?原图形被纵向拉伸2倍–4123456780–1–2–361234578910xy图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的如果横坐标保持不变,纵坐标变成原来的½,那么所得图案又会发生什么变化?原图形被纵向压缩1/2123456780–1–2–3–4–512345图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的横坐标保持不变,将各坐标的纵坐标都加2,则原图型变为什么样?yx原图形被纵向(向上)平移2个单位123456780–1–2–3–4–512345图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的横坐标保持不变,将各坐标的纵坐标都减1,则原图型变为什么样?yx原图形被向下平移1个单位123456780–1–2–3–4–512345图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的将各坐标的纵坐标都乘以-1,横坐标保持不变,则图形怎么变化?坐标变化为yx与原图形关于x轴对称(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(x,-y)(0,0)(5,-4)(3,0)(5,-1)(5,1)(3,0)(4,2)(0,0)–4123456780–1–2–361234578910xy1.图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的如果横坐标与纵坐标同时乘以2,那么所得图案又会发生什么变化?原坐标变为:原图形被横向、纵向各拉伸2倍原图形的形状没变,面积是原来的4倍。(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(2x,2y)(0,0)(10,8)(6,0)(10,2)(10,-2)(6,0)(8,-4)(0,0)–5图中的鱼是将坐标为:(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)的点用线段依次连接而成的将各坐标的纵坐标与横坐标都乘以-1,图形会变成什么样?yx234510–1–2–3–412345–1–2–3–4–5原坐标变为(0,0)(-5,-4)(-3,0)(-5,-1)(-5,1)(-3,0)(-4,2)(0,0)与原图形关于原点中心对称(x,y)(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)(-x,-y)(0,0)(-5,-4)(-3,0)(-5,-1)(-5,1)(-3,0)(-4,2)(0,0)一、平移1.纵坐标不变,横坐标分别增加(减少)a个单位时,图形平移a个单位;2.横坐标不变,纵坐标分别增加(减少)a个单位时,图形平移a个单位;向右(向左)向上(向下)二、伸长(压缩)3.纵坐标不变,横坐标分别变为原来的a倍,则图形为原来的a倍(a1)4.横坐标不变,纵坐标分别变为原来的a倍,则图形为原来的a倍(a1)5.横坐标与纵坐标同时变为原来的a倍,则图形为原来的a倍(a1)…横向伸长或图形横向缩短为原来的a倍(0a1)。纵向伸长或图形纵向缩短为原来的a倍(0a1)。纵、横向同时伸长三、轴对称6.纵坐标不变,横坐标分别乘-1,所得图形与原图形关于;7.横坐标不变,纵坐标分别乘-1,所得图形与原图形关于;Y轴对称X轴对称原点四、中心对称8.横坐标与纵坐标都乘-1,所得图形与原图形关于中心对称。123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4与左图三角形相比,右图中的三角形发生了怎样变化。右图中的直角三角形顶点的坐标发生怎样变化。123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4与左图三角形相比,右图中的三角形发生了怎样变化。右图中的直角三角形顶点的坐标发生怎样变化。123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4与左图三角形相比,右图中的三角形发生了怎样变化。右图中的直角三角形顶点的坐标发生怎样变化。123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4与左图三角形相比,右图中的三角形发生了怎样变化。右图中的直角三角形顶点的坐标发生怎样变化。123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4与左图三角形相比,右图中的三角形发生了怎样变化。右图中的直角三角形顶点的坐标发生怎样变化。–4123456780–1–2–361234578910xy如果横坐标乘以2再减去1,纵坐标不变,那么所得图案会发生什么变化?延伸P1433、4

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