4.3角度制的有关计算课件PPT.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,复习,有,_,的,_,组成的图形。（静态）,1,、角的概念,2,、角的表示方法,（,1,）用,三个大写字母,表示,;,用,一个大写字母,表示,;,（,3,）用,一个数字,表示；,（,4,）用,一个希腊字母,表示。,公共端点,两条射线,顶点,只有一个,表示,_,的字母一定要写在中间。,必须是以这个字母为顶点的角,_,。,一条,_,绕着它的,_,旋转而形成的。（动态）,射线,端点,1,如图，回答下列问题,.,C,D,B,A,（,1,）,ABD,与,ABC,是同一个角吗？,（,2,）能用一个大写字母表示的角有几个？,（,3,）以点,A,为顶点的角有哪几个？,以点,D,为顶点的角呢？,（,4,）图中共有多少个角？是哪些角？,2,4.3.1,角度制,第四章 图形认识初步,O,B,A,3,度,分,秒,60,60,3600,60,3600,60,(1),角的度量单位：,_,、,_,、,_.,度,分,秒,以度，分，秒为单位的角的度量制叫做,角度制,。,(2),度分秒的换算：,1=_,，,1=_.,60,60,4,注意：,角的度、分、秒是,60,进制,的，,这和计量时间的时、分、秒是一样的。,5,例,1,：填空,（,1,）,34.5,0,=,0,/,（,2,）,112.27,0,=,0,/,/,解：（,1,）,34.5,0,=34,0,+0.5,0,=34,0,+0.5,60,/,=34,0,+3 0,/,=34,0,30,/,（,2,）,112.27,0,=112,0,+0.2760,/,=112,0,+16.2,/,=112,0,+16,/,+0.260,/,=112,0,16,/,12,/,34,30,112,16,12,题型一：角度的换算,6,练习,(1),112.11,0,=_,_,解：（,1,）,112.11=112+0.1160,=112+6.6,=112+6+0.660,=112636,7,例,2,、把下列各题结果化成度,72,0,36,/,=_,0,37,0,14,/,24,/,=_,0,解,:(1)72,0,36,/,=72,0,+36,/,=72,0,+(3660),0,=72,0,+0.6,0,=72.6,0,8,(2)37,0,14,/,24,/,=37,0,+14,/,+24,/,=37,0,+14,/,+(2460),/,=37,0,+14,/,+0.4,/,=37,0,+14.4,/,=37,0,+(14.460),0,=37,0,+0.24,0,=37.24,0,9,练习,(2)5727=_,10,例,3,、加减法计算,解,:(1),原式,=(12+45),0,+(36+24),/,+(56+35),/,=57,0,+60,/,+91,/,=57,0,+61,/,+31,/,=58,0,+1,/,+31,/,=58,0,1,/,31,/,题型二：角度的加减法运算,(1)12,0,36,/,56,/,+45,0,24,/,35,/,(2)79,0,45,/,61,0,48,/,49,/,11,(2)79,0,45,/,61,0,48,/,49,/,解,:,原式,=79,0,44,/,60,/,61,0,48,/,49,/,=78,0,104,/,60,/,61,0,48,/,49,/,=(78-61),0,(104-48),/,(60-49),/,=17,0,56,/,11,/,12,例,4,、乘除法运算,(3)21,0,31,/,27,/,3 (4)63,0,21,/,39,/,3,(5)106,0,6,/,25,/,5,解,:,原式,=(213),0,(313),/,(273),/,=63,0,93,/,81,/,=63,0,94,/,21,/,=64,0,34,/,21,/,题型三：角度的乘除法运算,13,(4)63,0,21,/,39,/,3,解,:,原式,=(633),0,(213),/,(393),/,=21,0,7,/,13,/,(5)106,0,6,/,25,/,5,解,:,原式,=(1065),0,(65),/,(255),/,=21,0,(,66,5),/,(255),/,=21,0,13,/,(,85,5),/,=21,0,13,/,17,/,题型三：角度的乘除法运算,14,(1)52,0,49,/,12,/,+37,0,14,/,24,/,(2)82,0,-36,0,42,/,15,/,(3)35,0,36,/,47,/,9,(4)41,0,37,/,3,15,判断题：,（1）,两条射线组成的图形叫角,.,（2）,直线是一个平角,.,（,3,）,具有公共端点的两条射线组成角,.,（,4,）,角的两边是两条线段,.,（,5,）,18,时整，时针和分针成一个平角,.,相信你能行！,(),(),(),(),(,),16,学以致用,17,角的个数,2+1=3,3+2+1=6,4+3+2+1=10,O,A,1,A,2,A,3,A,16,O,A,1,A,2,A,3,A,n,16,条射线,n,条射线,角的个数,15+14+2+1=120,5,条射线,4,条射线,o,A,1,A,2,A,3,O,A,1,A,2,A,3,A,4,O,A,1,A,2,A,3,A,4,A,5,3,条射线,O,B,A,18,如图，棱锥表面上有几个角，请把它们表示出来？,A,B,C,D,练一练,BAC CAD BAD,ABC ABD CBD,ACB ACD BCD,ADB ADC BDC,19,下列关于钟表上时针与分针所成角的问题,（,1,）上午,8,时整，时针与分针成几度角？,（,2,）下午,7,时,55,分，时针与分针所成的角是等于,90,、大于,90,，还是小于,90,？,解：（,1,）上午,8,时整，时针与分针成,120,度角；,（,2,）上午,7,时,55,分，时针与分针所成的角大于,90,；,思考,20,