Ôn thi Tuyển Sinh 10 - Phần Hình Học - Câu 7

By Trang Ánh Nam -

Từ những miếng tôn phẳng hình chữ nhật có chiều dài 1,5 dm và chiều rộng 1,4 dm. Người ta tạo nên mặt xung quanh của những chiếc hộp hình trụ. Trong hai cách làm, hỏi cách nào thì được chiếc hộp có thể tích lớn hơn.

Lời giải

Cách 1: Chu vi đáy hình trụ là 1,5 dm, chiều cao hình trụ là h1 = 1,4 dm.

Hình trụ này có bán kính đáy diện tích đáy

 

thể tích  

Cách 2: Chu vi đáy hình trụ là 1,4 dm, chiều cao hình trụ là h2 = 1,5 dm.

Hình trụ này có

 

Ta có V1 > V2 nên cách 1 sẽ cho hình trụ có thể tích lớn hơn.

 

Lưu ý:
ü  Ô vuông là những kí hiệu bị lỗi do Word – thường là Góc

ü  Các bạn có thể xem thêm các bài Ôn Tuyển sinh Hình Học tại Đây: Hình Học 9

Comments

Post a Comment

Popular posts from this blog

NBC Washington Correspondent Yamiche Alcindor and former U.S. Attorney Barbara McQuade join Andrea Mitchell to discuss key challenges facing the January 6 Committee ahead of their primetime hearings this week: getting a "distracted nation" to pay attention and understand what's at stake. “I think the biggest challenge for lawmakers here, as they talk about these sort of huge ideas of American democracy and sort of the experiment that we're all living in, benefiting from, possibly being brought to his knees, is whether or not they can make people care,” says Alcindor. “The American public has been groomed to expect high value quick entertainment,” says McQuade. "I think putting together a polished show can be very important."

By -
Image
 NBC News correspondent Yamiche Alcindor worried Democrats would have a difficult time making Americans "care" and pay attention to the January 6 hearings, amid high gas prices, inflation, and a baby formula shortage. Appearing in a MSNBC panel Monday, Alcindor told host Andrea Mitchell that the "biggest challenge" the January 6 House Select Committee faced was getting Americans to have the same level of concern for their investigation. "I think the biggest challenge for lawmakers here as they talk about these sort of huge ideas of American democracy and sort of the experiment that we’re all living and benefiting from possibly being brought to his knees is whether or not they can make people care, Andrea," she said. Link 1 Link 2 Link 3 September 18 Post By Học Để Thi | Breaking News, Latest News and Videos Tranganhnam.xyz
Read more

Cuomo, Lemon discuss Trump's comments on race

By Trang Ánh Nam -
Image
Chris Cuomo and Don Lemon discuss President Donald Trump's comments about race after the 2019 Oscars. Be nice if Spike Lee could read his notes, or better yet not have to use notes at all, when doing his racist hit on your President, who has done more for African Americans (Criminal Justice Reform, Lowest Unemployment numbers in History, Tax Cuts,etc.) than almost any other Pres! — Donald J. Trump (@realDonaldTrump) February 25, 2019 The left loves to hate on Trump, calling him a racist and what not. I know Trump can be juvenile sometimes – certainly – but the racist and hateful name-calling is just what it is, garbage.
Read more

AOC calls out Times Square billboard criticism for Amazon snub on Twitter and shows who exactly is funding the billboards.

By Trang Ánh Nam -
Image
Alexandria Ocasio-Cortez scrambled Sunday to explain why neighbors at her listed Bronx address never saw her there — and ended up claiming she recently relocatedto a larger place nearby. The day after The Post reported that residents said they had never seen her around — and she ducked questions about it after an appearance — her spokesman said the Democratic freshman congresswoman now lives with her boyfriend in a two-bedroom apartment “a block and a half away.’’ The pair relocated there earlier this month, he said. “She lives in the same neighborhood she’s lived in for years,” said the spokesman, Corbin Trent. “She is not living in the exact same condo.’’ The recent move still didn’t explain why residents at her previous digs — a one-bedroom Bronx condo owned by her mom — insisted they had never seen her there. U.S. reps and senators are required to have a residence in their home districts. Trent claimed that Ocasio-Cortez, 29, was at her new home Sunday afternoon, al
Read more