1、第6课 画星星,2,海龟命令我知道,HT ST,cs home,FD BK,RT LT,PU PD PE,REPEAT,藏龟 显龟,清屏复位 复位,提笔 落笔 擦除,前进 后退,右转 左转,重复,3,画一个步长为100的正方形,FD 100 RT 90 FD 100 RT 90 FD 100 RT 90 FD 100 RT 90,Repeat 4FD 100 RT 90,4,7/22/2018,五角星,七角星,九角星,观察上面多角星的边和角各有什么特点？,每颗多角星的边相等、角相等,正多角星,7/22/2018,7/22/2018,7/22/2018,7/22/2018,边长,转动的角度,（外
2、角）,（内角）,7/22/2018,8,7/22/2018,7/22/2018,36,144,一个内角=180/5=36,一个外角=180-180/5=144,画一个边长为100步的正五角星,动动手,7/22/2018,7/22/2018,画一个边长为100步的正五角星,fd 100 rt 144 fd 100 rt 144 fd 100 rt 144 fd 100 rt 144 fd 100 rt 144,Repeat 5fd 100 rt 144,Repeat 5fd 100 rt 180-180/5,7/22/2018,11,7/22/2018,12,7/22/2018,13,得出结论,
3、角数为奇数的正多角星，它所有的内角总和正好是180度。,7/22/2018,7/22/2018,正多角星(奇数)： repeat _fd_ rt_或 lt,正七角星：Repeat 7fd 100 rt 180180/7,正九角星：Repeat 9fd 100 rt 180180/9,正十一角星：Repeat 11fd 100 rt 180180/11,角数,边长,180180/角数,正五角星：Repeat 5fd 100 rt 180180/5,7/22/2018,7/22/2018,大风车,7/22/2018,7/22/2018,fd 60 repeat 5fd 50 rt 180180/5 bk 60 rt 90 fd 60 repeat 5fd 50 rt 180180/5 bk 60 rt 90 fd 60 repeat 5fd 50 rt 180180/5 bk 60 rt 90 fd 60 repeat 5fd 50 rt 180180/5 bk 60 rt 90,Repeat 4 fd 60 repeat 5fd 50 rt 180180/5 bk 60 rt 90,大风车这样画,7/22/2018,各位星星，再见！,7/22/2018,
