补充：《角度的换算-角的计算》.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,*,角度的换算,1,自己动手，一定能行！,1,、分别画出,30,0,，,45,0,，,60,0,，,90,0,的角；,2,、你能画出,15,0,，,75,0,，,105,0,，,120,0,，,135,0,、,150,0,和,165,0,的角吗？画一画。,2,一,周角,=,2,平角,=,4,直角,=360,0,一,平角,=180,0,一,直角,=90,0,1,0,=60,/,1,/,=60,/,（读成,1,度等于,60,分，,1,分等于,60,秒 ）,请你要牢记哟,!,3,例题,1,填空,（,1,）,34.5,=,/,（,2,）,112.27,=,/,/,解：（,1,）,34.5,=34,+0.5,=34,+0.5,60,/,=34,+3 0,/,=34,30,/,（,2,）,112.27,=112,+0.2760,/,=112,+16.2,/,=112,+16,/,+0.260,/,=112,16,/,12,/,34,30,112,16,12,1,0,=60,/,1,/=,60,/,4,例题,2,把下列各题结果化成度,72,36,/,(2)37,14,/,24,/,解,:(1)72,36,/,=72,+36,/,=72,+(3660),=72,+0.6,=72.6,5,(2)37,14,/,24,/,=37,+14,/,+24,/,=37,+14,/,+(24,60),/,=37,+14,/,+0.4,/,=37,+14.4,/,=37,+(14.460),=37,+0.24,=37.24,6,角度换算,724=,194221”=,262542”=,6518”=,29.34=,38.15=,72.17=,54.03=,7,例题,3,计算,(1)12,36,/,56,/,+45,24,/,35,/,解,:(1),原式,=(12+45),+(36+24),/,+(56+35),/,=57,+60,/,+91,/,=57,+61,/,+31,/,=58,+1,/,+31,/,=58,1,/,31,/,8,(2)79,45,/,61,48,/,49,/,解,:,原式,=79,44,/,60,/,61,48,/,49,/,=78,104,/,60,/,61,48,/,49,/,=(78-61),(104-48),/,(60-49),/,=17,56,/,11,/,(3)21,31,/,27,/,3,解,:,原式,=(213,),(313),/,(273),/,=63,93,/,81,/,=63,94,/,21,/,=64,34,/,21,/,9,(4)63,21,/,39,/,3,解,:,原式,=(633),(213),/,(393),/,=21,7,/,13,/,(5)106,6,/,25,/,5,解,:,原式,=(1065),(65),/,(255),/,=21,(,66,5),/,(255),/,=21,13,/,(,85,5),/,=21,13,/,17,/,10,练习：,(1)283938”+524356”,(2)525943”+7430”,(3)90-2812,(4)180-5732,(5)4839,3,(6)6731”54”,4,(7)721854”,3,(8)27463”,9,11,(1),在某天的,13:15,时，时针与分针的夹角是多少度？,13:54,时呢？,(2),从,13:15,到,13:54,时钟的时针和分针各自转过的角度又分别是多少？,12,如图，直线,AB,、,CD,相交于,O,，,BOC=80,。,，,OE,是,BOC,的角平分线，,OF,是,OE,的反向延长线，（,1,）求,2,、,3,的度数；（,2,）说明,OF,是否平分,AOD,。,13,归纳：如何判定角平分线？,如图，下列条件中，只要满足任意一个，即可判断,OD,是,AOB,的角平分线,1.,AOD=,BOD,2.,AOD=1/2,AOB,3.,BOD=1/2,AOB,4.,AOB=2,AOD,5.,AOB=2,BOD,A,O,D,B,14,如图，OC是AOD的平分线，OE是BOD的平分线若AOB=130,，那么COE是多少度？,如图，,OC,是,AOD,的平分线，,OE,是,BOD,的平分线,(1),若,AOB=130,COE,是多少度？,(2),在,(1),的条件下，如果,DOC=20,，那么,BOE,是多少度,15,如图，,OD,是,AOC,的平分线，,OE,是,BOC,的平分线。（,1,）如果,AOC=48,，,BOC=42,，求,DOE,的度数。（,2,）如图,AOB,的大小不变，与（,1,）相同，而射线,OC,在,AOB,的内部绕点,O,旋转，,DOE,的大小是否发生变化？若不变，请求出其度数。（,3,）如果,AOB,的大小仍不变，而射线,OC,在,AOB,的外部绕点,O,旋转（,AOC,不大于,90,），,OD,是,AOC,的平分线，,OE,是,BOC,的平分线，请画出相应的图形，此时,DOE,的大小是否发生变化？并说明理由。,16,