《2022年人教版数学九下28.1《锐角三角函数》word导学案1 .pdf》由会员分享,可在线阅读,更多相关《2022年人教版数学九下28.1《锐角三角函数》word导学案1 .pdf(4页珍藏版)》请在得力文库 - 分享文档赚钱的网站上搜索。
1、名师精编优秀教案28.1锐角三角函数(1)正弦【学习目标】1经历当直角三角形的锐角固定时,它的对边与斜边的比值都固定(即正弦值不变)这一事实。2能根据正弦概念正确进行计算【学习重点】理解正弦(sinA)概念,知道当直角三角形的锐角固定时,它的对边与斜边的比值是固定值这一事实【学习难点】当直角三角形的锐角固定时,它的对边与斜边的比值是固定值的事实。一、旧知回顾1、如图在 Rt ABC 中,C=90,A=30,BC=10m,求 AB 2、如图在 Rt ABC 中,C=90,A=30,AB=20m,求 BC 二、新知学习问题:为了绿化荒山,某地打算从位于山脚下的机井房沿着山坡铺设水管,在山坡上修建一
2、座扬水站,对坡面的绿地进行喷灌 现测得斜坡与水平面所成角的度数是 30,为使出水口的高度为35m,那么需要准备多长的水管?思考 1:如果使出水口的高度为50m,那么需要准备多长的水管?;如果使出水口的高度为a m,那么需要准备多长的水管?;结论:直角三角形中,30 角的对边与斜边的比值思考 2:在 Rt ABC 中,C=90 ,A=45 ,A 对边与斜边的比值是一个定名师精编优秀教案CBA值吗?如果是,是多少?结论:直角三角形中,45 角的对边与斜边的比值教师点拨:从上面这两个问题的结论中可知,在一个 Rt ABC 中,C=90 ,当A=30 时,A 的对边与斜边的比都等于12,是一个固定值;
3、当A=45 时,A 的对边与斜边的比都等于22,也是一个固定值这就引发我们产生这样一个疑问:当A 取其他一定度数的锐角时,它的对边与斜边的比是否也是一个固定值?探究:任意画 Rt ABC 和 Rt ABC,使得 C=C=90,A=A=a,那么BCB CABA B与有什么关系你能解释一下吗?结论:这就是说,在直角三角形中,当锐角A 的度数一定时,不管三角形的大小如何,A 的对边与斜边的比正弦函数概念:规定:在 Rt BC 中,C=90,A 的对边记作 a,B 的对边记作 b,C 的对边记作 c在 Rt BC 中,C=90 ,我们把锐角 A 的对边与斜边的比叫做 A 的正弦,记作 sinA,即 s
4、inA=acsinAAaAc的对边的斜边例如,当 A=30 时,我们有 sinA=sin30=;文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:C
5、Y2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 H
6、P4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM
7、3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码
8、:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10
9、 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5
10、ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3名师精编优秀教案(2)1353CBA(1)34CBA当A=45 时,我们有 sinA=sin45=学生展示:例 1 如图,在 Rt ABC 中,C=90 ,求 sinA
11、 和 sinB 的值随堂练习:做课本第 64 页练习三、知识梳理在直角三角形中,当锐角A 的度数一定时,不管三角形的大小如何,A 的对边与斜边的比都是在 Rt ABC 中,C=90 ,我们把锐角 A 的对边与斜边的比叫做 A 的,记作,四、学习评价【当堂检测】1三角形在正方形网格纸中的位置如图所示,则sin 的值是A43B34C53D542如图,在直角 ABC 中,C90o,若 AB5,AC4,则 sinA()A35B45C34D433 在 ABC 中,C=90,BC=2,sinA=23,则边 AC 的长是()A13 B3 C43D5 4如图,已知点 P 的坐标是(a,b),则 sin 等于(
12、)文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6
13、Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1
14、B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J
15、9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7
16、O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4
17、G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y
18、9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3名师精编优秀教案AabBbaC2222.abDabab作业设置:习题 28.1 复习巩固第 1 题、第 2 题(只做与正弦函数有关的部分)【自我评价】1本节课有困惑的题目是:2本节课的学习收获是:文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3
19、E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:
20、CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10
21、HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 Z
22、M3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编
23、码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T1
24、0 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3文档编码:CY2X7O6Y9T10 HP4P4G1B2E5 ZM3E6Y9J9E3