在日常生产、生活中,经常把同样大小的圆柱管捆扎起来(接头处忽略不计),每根圆柱管的直径都是10厘米,捆扎后的横截面如下图所示:
请你根据图示,探索发现求绳子长度的方法,并完成下表:
圆柱管的根数
1
2
3
4
…
10
绳子长度(cm)
解:①π×10=10π(厘米);
②10π+20(厘米);
③10π+20×2=10π+40(厘米);
④10π+20×3=10π+60(厘米);
⑤10π+20×(10﹣1)=10π+180(厘米);
统计表如下:
设x是实数,且满足等式x2+12x=cosΘ,则实数Θ等于( )(以下各式中k∈Z)
读一读,判断正(T)误(F)。
It's sunny today. Peter and his friendshave a picnic in the park. They're very happy. Peter: What do you have, Joe?
Joe: I have someapples. They are so sweet. What about you, Peter?
Peter: I havesome cakes, some biscuits and some fruit juice.
Kitty: Wow! Ihave some sweets and some bread. Would you like some bread, Alice?
Alice: Sure, Ilike bread very much. And I have a kite. Then we can fly a kite.
Peter: OK,let's have our picnic now.
Kitty: Goodidea!
下图是沿某经线我国局部地区地形剖面图(实线表示),①②③曲线代表一月平均气温、年降水量、日平均气温≥10℃的积温,读图回答题。①②③三条曲线分别代表: