问题
选择题
在正方体ABCD-A1B1C1D1中，已知AC=2
|
答案
∵在正方体ABCD-A1B1C1D1中，AC=2
，6
∴设正方体的棱长为a，则
a=22
，解得a=26
．3
因此，这个正方体内切球的直径2R=2
，解得R=3
，3
∴正方体内切球的体积为V=
πR3=4 3
π•(4 3
)3=43
π．3
故选：C
搜题请搜索小程序“爱下问搜题”
在正方体ABCD-A1B1C1D1中，已知AC=2
|
∵在正方体ABCD-A1B1C1D1中，AC=2
，6
∴设正方体的棱长为a，则
a=22
，解得a=26
．3
因此，这个正方体内切球的直径2R=2
，解得R=3
，3
∴正方体内切球的体积为V=
πR3=4 3
π•(4 3
)3=43
π．3
故选：C
We come by business naturally in our family.Each of the seven children in our family worked in our father’s store.As we worked and watched，we ____ that work was about more than ____ and making a sale. One lesson stands out in my mind.It was shortly before Christmas.I was in eighth grade and was working evenings，straightening the toy section.A little boy，five or six years old，came in.He was wearing a brown torn coat with ____ sleeves.His shoes were scuffed(磨损) and his one shoelace was torn.The little boy looked poor to me—too poor to ____ to buy anything.He looked around the toy section，picked up this item and that，and ____ put them back in their place. Dad came down the stairs and walked over to the boy.His steel blue eyes ____ and the dimple(酒窝) in his cheek stood out as he ____ the boy what he could do for him.The boy said he was looking for a Christmas ___ for his brother.I was impressed that Dad treated him with the same ____ as any adult.Dad told him to take his ___ and look around.He did. After about 20 minutes，the little boy picked up a toy plane，walked up to my dad and said, “How much for this，Mister？” “How much you ____？” Dad asked. The little boy held out his hand and ___ it.His hand was creased(起皱) with ____ lines of dirt from holding his ____ too tightly.In his hand lay only 27 cents.The ____ on the toy plane he’d ____ was $3.98. “That’ll just ___ it，” Dad said as he made the sale.Dad’s reply still ____ in my ears.When the little boy walked out of the store，I didn’t notice the worn coat or the ____ torn shoelace.What I saw was a happy child with a ____.
|