Hình 9, nhờ các anh chị và các bạn giúp dùm câu cuối nhe! Cám ơn?

By Trang Ánh Nam -

Hình 9, nhờ các anh chị và các bạn giúp dùm câu cuối nhe! Cám ơn?

Cho đường tròn (O), đường kính AB. Lấy C thuộc đường tròn (O) (C khác A,B). Tiếp tuyến tại A của đường tròn (O) cắt BC tại M. 

a) Chứng minh: tam giác ABC là tam giác vuông (Đã giải được) 

b) Gọi K là trung điểm MA. Chứng minh: KC là tiếp tuyến của đường tròn (O) và KO là đường trung trực của AC.(Đã làm được) 

c) KC cắt tiếp tuyến tại B của đường tròn (O) tại D. Chứng minh: 
OM vuông góc với AD. (Câu này khó quá, chưa giải ra) 

Nhờ tất cả giải dùm câu cuối nhe!

Giải:

d. gọi N là giao điểm của AC và BD.

Xét tam giác BCN , ta có:

ü BCN vuông tại C (giả thuyết)

ü CD=BD (tình chất 2 tiếp tuyến cắt nhau)

=>ND=DB=CD (dừơng trung tuyến trong tam giác vuông)

Xét 2 tam giác AMB và BAN, ta có:

Suy ra:ABM đồng dạng với BNA

Lại có:

ü MO là trung tuyến của ABM (gt)

ü AD là trung tuyến của BNA  (cmt)

Nên: AMO đồng dạng với BAD

=>

Mà:

Suy ra:

ð Tam giác AHO vuông tại H.

ð AD⊥MO

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