cho tam giác ABC cân tại A . Vẽ AH xuông góc với BC tại H . Vẽ HD vuông góc với AB tại D , HE vuông góc với AC tại E . chứng minh rằng
a) BH = HC
b) BD = CE
cho tam giác ABC cân tại A vẽ AH vuông góc BC tại H . Vẽ HD vuông góc vớ AB tại D , HE vuông góc với AC tại E. chứng minh Bd = CE
mà thằng hiếu nhá,ko nick nào tao kb với mày đâu
CHO TAM GIÁC ABC CÂN TẠI A. VẼ AH VUÔNG GÓC BC . HD VUÔNG GÓC AB TẠI D, HE VUÔNG GÓC AC TẠI E. CHỨNG MINH
A, BH=CH
B,BD=CE
TA CÓ \(\Delta ABC\)CÂN TẠI A
\(\Rightarrow\hept{\begin{cases}AB=AC\\\widehat{B}=\widehat{C}\end{cases}}\)
A) VÌ AH VUÔNG GÓC VỚI BC
=> AH LÀ ĐƯỜNG CAO
MÀ TRONG TAM GIÁC CÂN ĐƯỜNG CAO CŨNG CHÍNH LÀ ĐƯỜNG TRUNG TUYẾN
=> AH LÀ TRUNG TUYẾN CỦA BC
=> BH=CH(ĐPCM)
B) XÉT TAM GIÁC NHA
Vì tam giác ABC cân tại A suy ra AB=AC, góc B=góc C
Xét tam giác ABH và tam giác ACH
có AB=AC(CMT)
góc AHC=góc AHB (=900)
góc B=góc C
suy ra tam giác ABH = tam giác ACH (cạnh huyền-góc nhọn)
suy ra BH=CH (hai cạnh tương ứng)
b) Xét tam giac BHD và tam giác CHE
có BH=CH (CMT)
góc B=góc C
góc HDB = góc HEC = 900
suy ra tam giac BHD = tam giác CHE (cạnh huyền-góc nhọn)
suy ra BD=CE (hai cạnh tương ứng)
Cho tam giác ABC cân tại A, vẽ AH vuông góc với BC tại H, vẽ HD vuông góc với AB tại D, HE vuông góc với AC tại E. CMR :
a, AH = HC
b, BD = CE
ho tam giác ABC vuông tại A, AH vuông góc với BC. a) Cho BH = 4cm, CH = 2cm. Tính AB, AC. b) Vẽ HD vuông góc với AB tại D, HE vuông góc với AC tại E. Chứng minh BD = BC.cos^3B; DE^3 = BD . CE. BC
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 cân tại B kẻ BH vuông góc với AC ( H thộc AC)
a/ chứng minh :HA = HC
b/kẻ HD vuông góc AB ( D thuộc AB), HE vuông góc BC ( E thuộc BC) chứng minh HD=HE
c/ chứng min tam giác AED là tam giác cân
1. cho tam giác ABC cân tại A. Trên tia đối của tia BC lấy điểm D. Vẽ AH vuông góc với BC tại H. So sánh HC và HD
3. cho tam giác ABC có góc B,C nhọn. Vẽ AH vuông góc với BC tại H. cm: AB+AC > 2AH
4. cho tam giác ABC nhọn. Vẽ BC vuông góc với AC tại D, vẽ CE vuông góc với AB tại E. cm: BC+CE < AB+AC
giải giúp mik với!!!! -_- "_" "_"
1. cho tam giác ABC cân tại A. Trên tia đối của tia BC lấy điểm D. Vẽ AH vuông góc với BC tại H. So sánh HC và HD
3. cho tam giác ABC có góc B,C nhọn. Vẽ AH vuông góc với BC tại H. cm: AB+AC > 2AH
4. cho tam giác ABC nhọn. Vẽ BC vuông góc với AC tại D, vẽ CE vuông góc với AB tại E. cm: BC+CE < AB+AC
giải giúp mik với!!!! -_- "_" "_"
1.
Ta có : AC<AD (vì : D là tia đối của tia BC )
=> HD<HC
3.
Ta có : AB+AC>AH (vì : tog 2 cah cua tam giác luôn lớn hơn cah con lại)
Mà : 1/2AH<AB+AC
=> AB+AC>2AH
4.
Ta có : ko hiu
bạn giải bài 3 mik hk hiu, bn viết rõ rak dc hk