题目

在同一平面内，将两块正三角形的纸板的两个顶点重合在一起．（1）如图1重叠部分∠AOD=30°，求∠COB的大小；（2）如图2重叠部分∠AOD=15°，求∠COB的大小；（3）如图3，若两图形除O外没有重叠，∠AOD=10°，求∠COB的大小；（4）求∠AOD和∠COB的数量关系． 答案：【答案】（1）∠COB=90°；（2）∠COB=105°；（3）∠COB=130°；（4）①当∠AOD是两个角的重叠的角，∠COB=120°-∠AOD；②当∠AOD是两个角的相离时的角，且小于或等于60°，∠COB=120°+∠AOD；③当∠AOD是两个角的相离时的角，且大于60°，∠COB=240°-∠AOD．【解析】（1）根据题意用∠COD＋∠AOB的和减去∠AOD的值即I have a sister. My lifestyle is different from her. I 1 healthier than her. I exercise twice a day. Usually I come home from school 2 , though my home is 3  from school. It takes me more than one hour. And my eating 4  are better than hers. She often has a 5  , because she likes to eat unhealthy diet. 6  I don’t like milk, my mother wants me to drink it. She says it’s good for my health. So I have to drink it. I try to eat 7 vegetables ten to eleven times a week. I keep eating fruit every day. They help me to keep in good health. As 8  meat, I must try to eat less of it. Of course, I love junk food too. I try to eat it only 9 a week. I sleep for nine hours every night. 10 you see, my healthy lifestyle depends on good food and exercise. It helps me study better. 【小题1】A．amB．isC．areD．was【小题2】A．on feetB．on footC．by footD．on bike【小题3】A．differentB．nearC．farD．come【小题4】A．habitB．hobbyC．habitsD．health【小题5】A．headacheB．sore throatC．stomachacheD．sore back【小题6】A．SoB．AlthoughC．AndD．But【小题7】A．muchB．a littleC．anyD．more【小题8】A．toB．forC．fromD．of【小题9】A．onceB．twiceC．three timesD．four times【小题10】A．ButB．SoC．BecauseD．And