Thi HSG
Chia sẻ bởi Nguyễn Trọng Diễn |
Ngày 16/10/2018 |
45
Chia sẻ tài liệu: Thi HSG thuộc Hình học 7
Nội dung tài liệu:
Phòng gd & đt phúc thọ bài thi thử hsg 2007 -2008
Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài: Cho tam giác ABC nhọn. Hãy chứng minh:
a, + +
b, Sin Sin Sin .
c, Sin A + Sin B + Sin C < 2 ( Cos A + Cos B + Cos C ).
Bài làm:
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Phòng gd & đt phúc thọ bài thi thử hsg 2007 -2008
Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài:
Cho tam giác ABC và điểm M nằm trong tam giác đó,ký hiệu da ,db,dc là các khoảng cách từ M các cạnh tương ứng tam giác,S là diện tích tam giác.Hãy chứng minh :
a, a.MA + b.MB + c.MC ≥ 4S ;
b, a.MA ≥ b.db + c.dc ;
c, MA + MB + MC ≥ 8da.db.dc ;
d, MA + MB + MC ≥ 2( da + db + dc ) ;
e, ( da + db + dc ) > 2 r ; ha + hb + hc ≥ 9.r ; MA + MB + MC ≥ 6.r .
f,Tìm M để ( da2 + db2 + dc2 ) đạt min ?
h,Tìm M để + + đạt min ?
Bài làm:
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Phòng gd & đt phúc thọ bài thi thử hsg 2007 -2008
Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài: Cho tam giác ABC và kéo dài các đường trung tuyến AA’,BB’,CC’ của nó cắt đường tròn ngoại tiếp tam giác đó tại M,N,E. Hãy chứng minh :
a, 4.AA’ = 2b 2 + 2c 2 – a 2
b, + +
Bài làm :
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Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài: Cho tam giác ABC nhọn. Hãy chứng minh:
a, + +
b, Sin Sin Sin .
c, Sin A + Sin B + Sin C < 2 ( Cos A + Cos B + Cos C ).
Bài làm:
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Phòng gd & đt phúc thọ bài thi thử hsg 2007 -2008
Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài:
Cho tam giác ABC và điểm M nằm trong tam giác đó,ký hiệu da ,db,dc là các khoảng cách từ M các cạnh tương ứng tam giác,S là diện tích tam giác.Hãy chứng minh :
a, a.MA + b.MB + c.MC ≥ 4S ;
b, a.MA ≥ b.db + c.dc ;
c, MA + MB + MC ≥ 8da.db.dc ;
d, MA + MB + MC ≥ 2( da + db + dc ) ;
e, ( da + db + dc ) > 2 r ; ha + hb + hc ≥ 9.r ; MA + MB + MC ≥ 6.r .
f,Tìm M để ( da2 + db2 + dc2 ) đạt min ?
h,Tìm M để + + đạt min ?
Bài làm:
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Phòng gd & đt phúc thọ bài thi thử hsg 2007 -2008
Họ và tên:................................................. Môn thi: Toán -Lớp 9
Trường .....................................................
Điểm
Lời phê của thầy giáo
Đề bài: Cho tam giác ABC và kéo dài các đường trung tuyến AA’,BB’,CC’ của nó cắt đường tròn ngoại tiếp tam giác đó tại M,N,E. Hãy chứng minh :
a, 4.AA’ = 2b 2 + 2c 2 – a 2
b, + +
Bài làm :
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