Cho tam giác ABC vuông tại A với M(1;-2) là trung điểm BC. Viết phương trình đường tròn ngoại tiếp tam giác ABC biết AB=4, AC=6
1, cho tam giác ABC vuông tại A, vẽ đường cao AH. biết chu vi của tam giác ABH bằng 30cm, chu vi tam giác ACH bằng 40cm. Tính chu vi tam giác ABC
2, cho tam giác ABC vuông tại a, Ah vuông với Bc tại H. Tia phân giác của góc ABH cắt AH tại M. Kẻ đướng vuông góc với BM tại B, nó cát tia AH tại N. Chứng minh: BC.HN=AB.NA
giúp mình với.......
Bài 1: Cho tam giác ABC vuông tại A, AB = 6cm, BC = 10cm, điểm D thuộc AC sao cho DC = 3cm. Qua D kẻ đường thẳng vuông góc với AC và cắt cạnh BC tại M. Đường thẳng vuông góc với BC tại M cắt BA tại E. Chứng minh:
a) tam giác ABC đồng dạng với tam giác MDC. Tính độ dài MD, MC.
b) tam giác ABC đồng dạng với tam giác MBE và BE.BA = BM.BC
c) góc BMA= góc BEC
Bài 2: Cho ABC có AB = 14cm, AC = 10cm, CB = 12cm. Đường phân giác của C cắt cạnh BC ở D.
a) Tính độ dài các đoạn thẳng BD, DC.
b) Tính tỉ số diện tích của ABD và !ACD.
c) Qua D kẻ đường thẳng song song với AB cắt cạnh AC ở E. Tính DE, AE, EC
Ai đó làm ơn làm Phước giúp mình bài 1 với câu c bài 2 với ạ
Xin mọi người đó😭
1. Cho tam giác ABC vuông tại A. Từ M trong tam giác vẽ IM vuông góc BC, JM vuông góc CA, KM vuông góc AB. Xác định M sao cho MI^2+MJ^2+MK^2 đạt GTNN
2. tam giác ABC vuông tại A. Trên cạnh AB, BC, CA lần lượt lấy K, L, M sao cho tam giác KLM vuông cân tại C. Xác định vị trí K, L, M để diện tích tam giác KML đạt GTNN
3. Cho tam giác ABC vuông tại A. M, N là 2 điểm lần lượt trên AB và AC sao cho AM=1/3AB và AN=1/3AC. biết độ dài BN =sin a. CM: cos a với a<90 độ....
Cho tam giác ABC vuông tại A(AB<AC) có AH là đường cao
1)CMR: Tam giác ABC đồng dạng với tam giác HAC và AC^2=CH.CB
2) Đường thẳng vuông góc với BC tại C cắt tia BA tạị M vẽ AI vuông góc với CM tại I.CMR tam giác CHI đồng dạng với tam giác CMB
Bài 1 : Cho xOy có Oz là tia phân giác, M là điểm bất kì thuộc tia Oz. Qua M kẻ đường thẳng a vuông góc với Ox tại a cắt Oy tại C và vẽ đường thẳng b vuông góc với Oy tại B cắt tia Ox tại D. Chứng minh tam giác AOM bằng tam giác BOM ?
Bài 2 : Cho tam giác ABC có góc A = 90* và đường phân giác BH (H thuộc AC). Kẻ HM vuông góc với BC (M thuộc BC). Gọi N là giao điểm của AB và MH. Chứng minh tam giác ABH bằng tam giác MBH, tam giác ACE= tam giác AKE?
Bài 3: Cho tam giác ABC vuông tại C có góc A = 60* và đường phân gác của góc BAC cắt BC tại E. Kẻ EK vuông góc AB tại K (K thuộc AB). Kẻ BD vuông góc với AE tại D (D thuộc AE). Chứng minh tam giác ACE = tam giác AKE
Bài 4: Cho tam giác ABC vuông tại A có đường phân giác của góc ABC cắt AC tại E. Kẻ EH vuông góc BC tại H (H thuộc BC). Chứng minh tam giác ABE = tam giác HBE ?
1. Cho tam giác ABC vuông ở A có AB<AC. AH vuông góc với BC tại H, D là điểm trên cạnh BC sao cho AD=AB. Vẽ DE vuông góc với BC tại E. Chứng mih rằng AH=HE.
2. Cho tam giác ABC vuông cân tại A.. Qua A vẽ đường thẳng d ở ngoài tam giác ABC . Vẽ BD vuông góc với d taị D. CE vuông góc với d tại E. M là trung điểm CB. Chứng minh rằng:
a) BD + CE = DE
b) Tam giác MDE là tam giác vuông cân
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Cho tam giác ABC vuông tại A, AB = 6cm, BC = 10cm, điểm D thuộc AC sao cho DC = 3cm. Qua D kẻ đường thẳng vuông góc với AC và cắt cạnh BC tại M. Đường thẳng vuông góc với BC tại M cắt BA tại E. Chứng minh:
a) tam giác ABC đồng dạng với tam giác MDC. Tính độ dài MD, MC.
b) tam giác ABC đồng dạng với tam giác MBE và BE.BA = BM.BC
c) góc BMA= góc BEC
a: Xét ΔABC vuông tại A và ΔDMC vuông tại D có
góc C chung
=>ΔABC đồng dạng với ΔDMC
=>AB/DM=BC/MC=AC/DC
=>6/DM=10/MC=8/3
=>DM=6:8/3=2,25cm và MC=10:8/3=10*3/8=30/8=3,75cm
b: Xét ΔABC vuông tại A và ΔMBE vuông tại M có
góc B chung
=>ΔABC đồng dạng với ΔMBE
=>BA/BM=BC/BE
=>BA*BE=BM*BC
cho tam giác ABC vuông tại A. Về phía ngoài tam giác ABC, vẽ tam giác ABC vuông cân tại A. Vẽ tam giác ACE vuông cân tại E.C/m rằng BDEC là hình thang cân
Giúp mình với nha!!!!!!!!!!!!!!!!!!!!!
Cho tam giác ABC cân tại A, kẻ AH vuông góc với BC tại H.
a) C/m: tam giác AHB= tam giác AHC
b) Kẻ HM vuông góc với AB tại M. Kẻ HN vuông góc với C tại N. C/m: tam giác AMN cân
c) C/m: AH vuông góc với MN
Giải nhanh giúp mik với ạ. Mai mik phải thi rồi🥺🥺
a: Xét ΔAHB vuông tại H và ΔAHC vuông tại H có
AB=AC
AH chung
Do đó: ΔAHB=ΔAHC
b: Xét ΔAHM vuông tại M và ΔAHN vuông tại N có
AH chung
\(\widehat{MAH}=\widehat{NAH}\)
Do đó: ΔAHM=ΔAHN
Suy ra: AM=AN
hay ΔAMN cân tại A
c: Ta có: AM=AN
HM=HN
Do đó: AH là đường trung trực của MN
hay AH⊥MN
Xét ΔAHB vuông tại H và ΔAHC vuông tại H có
cạnh AH chung
AB=AC(vì tam giác ABC cân tại A)
=> ΔAHB=ΔAHC(c.h-c.g.v)
Xét ΔAHM vuông tại M và ΔAHN vuông tại N có
\(\widehat{HAM}=\widehat{HAN}\)
cạnh AH chung
==> ΔAHM=ΔAHN(c.h-g.n)
==> AM=AN
=> ΔAMN cân tại A ( dấu hiệu)
c)Ta có:HM=HN ; AM=AN
===>AH là đường trung trực của MN
=>\(\text{AH⊥MN}\)
cho tam giác ABC vuông tại a,ABlớn hơn AC. M là 1 điểm tùy ý trên cạnh BC.Qua M kẻ đường thẳng vuông góc với BC, đường thẳng này cắt đoạn AB tại E và cắt đường thẳng AC tại F.
a, chứng minh tam giác ABC đồng dạng với tam giác MFC.
b, chứng minh:BE nhân BA bằng BM nhân BC.
c,chứng minh BAM bằng ECB. Gọi K là giao điểm của đường thẳng CE và BF.
chứng minh AB là phân giác của góc MAK.
giúp e nốt bài này với ạh
a: Xét ΔCAB và ΔCMF có
góc CAB=góc CMF
góc C chung
=>ΔCAB đồng dạng với ΔCMF
b: Xét ΔBME và ΔBAC có
góc BME=góc BAC
góc B chung
=>ΔBME đồng dạng với ΔBAC
=>BM/BA=BE/BC
=>BE*BA=BM*BC
c: góc CME+góc CAE=180 độ
=>CAEM nội tiếp
=>góc BAM=góc ECB