Cho tam giác ABC vuông tại A. Gọi D là trung điểm của AB. Kẻ DE vuông góc với BC( E thuộc BC ) .Tính độ dài AC biết BE=7cm, EC=25cm
Giúp mk vs nha các bn. Mk cần gấp!!!
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Cho tam giác ABC vuông tại A, gọi D là trung điểm của AB. kẻ DE vuông góc với BC (E thuộc BC). Tính AC biết: BE = 7cm, EC = 25cm.
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Cho tam giác ABC vuông tại A. Gọi D là trung điểm của AB. Kẻ DE vuông góc với BC( E thuộc BC ) .Tính độ dài AC biết BE=7cm, EC=25cm
Cho tam giác ABC vuông tại A. Gọi D là trung điểm của AB. Kẻ DE vuông góc với BC (E thuộc BC). Tính độ dài AC, biết BE = 7 cm, EC = 25 cm
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cho tam giác abc vuông tại a gọi d là trung điểm ab kẻ de vuông góc với bc (e thuộc bc) tính độ dài ac biết be =7 ec = 25 cm
Cho tam giác ABC vuông tại A. D là trung điểm của AB, kẻ DE vuông góc với BC (E thuộc BC) .Tính độ dài AC biết BE = 7cm, AC = 25cm
Ai giải giúp mình bài này với minh cần gấp; Cho tam giác ABC vuông tại A, đường phân giác BE (E thuộc AC) . Kẻ EH vuông góc BC (H thuộc BC). Gọi K là giao điểm của AB và HE. biết AB=6cm và BC=10cm. Câu a: Tính độ dài AC . Câu b: Chứng minh AB=HB, AE<EC . Câu c: chứng minh BE vuông góc CK và AH song song KC. Câu d: nếu góc ABC= 60 độ thì tam giác BHA là tam giác gì vì sao
cho tam giác ABC có góc A =90 độ .tia phân giác của góc ABC cắt AC tại E .qua E kẻ EH vuông góc với BC (H thuộc BC)
1,chứng minh tam giác ABE=HBE
2,chứng minh BE là đường trung trực của AH
3,chứng minh EA <EC
4,gọi K là giao điểm của AB và HE .chứng minh BE vuông góc với CK ;AH song song với CK
giúp mk vs ạ.mk đg cần gấp
Cho tam giác ABC vuông tại A, biết AB=6cm ,AC=8cm. Gọi M là trung điểm của đoạn thẳng BC
a, Tính độ dài BC,AM
b, Kẻ MDvuong góc AB (Dthuoc AB) ME vuông góc AC ( E thuoc AC) . Tứ giác ADME là hình gì?
c, Tam giác ABC có đk gì để tứ giác ADME là hình vuông ?
d, Gọi F đx với A qua M . Kể FH vuông góc vs BC ( H thuộc BC ) Gọi K là trung điểm của BH. CM : FK vuông góc vs EK ?
8
Cho tam giác ABC vuông tại A, trên cạnh BC lấy điểm D sao cho BA=BD. Từ D kẻ đường thẳng vuông góc với BC, cắt AC tại E.
a) Cho AB=5cm, AC=7cm, tính BC?
b) CMR: tam giác ABE= tam giác DBE
c) Gọi F là giao điểm của DE và BA, chứng minh:EF=EC
d) CMR: BE là trung trực của đoạn thẳng AD.
a) Áp dụng pytago .
b) Xét t/g ABE; tg DBE:
AB = DB ( gt)
g ABE = DBE (suy từ gt)
BE chung
=> tg ABE = tg DBE (c.g.c)
c) Vì tg ABE = tg DBE (câu b)
=> AE = DE
Xét tg AEF ⊥⊥ tại A; tg DEC ⊥⊥ tại D:
AE = DE (c/m trên)
g AEF = g DEC (đối đỉnh)
=> tg AEF = tg DEC (cgv - gn)
=> EF = EC
d) Do tg AEF = tg DEC (câu c)
=> AE = DE
=> E ∈∈ đg trung trực của AD (1)
Lại do AB = BD (gt)
=> B ∈ đg trung trực của AD (2)
Từ (1) và (2) => BE là đg trung trực của AD.
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a) Áp dụng định lí pytago cho \(\Delta ABC\):
\(BC^2=AB^2+AC^2\)
\(BC^2=5^2+7^2\)
\(BC^2=25+49\)
\(BC^2=74\)
\(BC=\sqrt{74}\)
\(\Rightarrow BC=\sqrt{74}\)
Chúc bn hk tốt :D