变化的鱼市名师优质课比赛一等奖市公开课获奖课件

5.3鱼的变化第1页12345-1-2-30–1–2–3–4–51234-4-55图中鱼是将坐标为：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)点用线段依次连接而成yx两个图形关于y轴对称要得到两个关于y轴对称图形：将各坐标纵坐标保持不变，横坐标都乘以－１。顶点坐标改变：(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)观察坐标系中两条鱼位置关系？第2页123456780–1–2–3–4–512345图中鱼是将坐标为：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)点用线段依次连接而成将各坐标纵坐标都乘以－1，横坐标保持不变，则图形怎么改变？坐标改变为：yx猜一猜与原图形关于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)第3页–5图中鱼是将坐标为：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)点用线段依次连接而成将各坐标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)猜想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)第4页–4123456780–1–2–361234578910xy1.图中鱼是将坐标为：(0,0)(5,4)(3,0)(5,1)(5,-1)(3,0)(4,-2)(0,0)点用线段依次连接而成假如横坐标与纵坐标同时乘以２，那么所得图案又会发生什么改变?

原坐标变为：原图形被横向、纵向各拉伸2倍原图形形状没变，面积是原来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)第5页三、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。第6页123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4练一练与左图三角形相比，右图中三角形发生了怎样改变。右图中直角三角形顶点坐标发生怎样改变。yyxx第7页123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4练一练与左图三角形相比，右图中三角形发生了怎样改变。右图中直角三角形顶点坐标发生怎样改变。第8页123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4练一练与左图三角形相比，右图中三角形发生了怎样改变。右图中直角三角形顶点坐标发生怎样改变。第9页123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4练一练与左图三角形相比，右图中三角形发生了怎样改变。右图中直角三角形顶点坐标发生怎样改变。第10页123410432–2–1–1–2–3–4–3–4123410432–2–1–1–2–3–4–3–4练一练与左图三角形相比，右图中三角形发生了怎样改变。右图中直角三角形顶点坐标发生怎样改变。第11页–4123456780–1–2–36