cho tam giac abc co goc c+90 do=goca ve ah vuong goc bc duong thang vuong goc voi ab tai a cat bc tai d goi m la giao diem cua cac tia phan giac goc bah va adh chung minh goc bah=2c chung minh mavuong goc ac

cho tam giac abc co goc a=90 do,giai tam giac abc biet ab=6cm,goc b=60 do

cho tam giac ABC va O nam trong tam giac do

a)CMR: goc BOC=goc A+ goc ABO+goc ACO

b)biet gocABO + goc ACO=90 do - gocA/2 va BO la tia p/g goc C

CMR:CO la tia p/g goc C

Cho tam giac ABC, biet B=50do, C=30 do

Tinh cac goc ngoai tai dinh A,B,C; Ve hinh minh hoa

   giup mink☹

1.cho tam giac ABC co goc B-C=alpha phan giac AD

a) tinh gocADC,ADB theo alpha

b)Ve duong cao AH tinh goc HAD

2.chotam giac ABC,gocA =alpha,cac tia ohan giac cua  B va C cat nhay tai I.Phan giac cat goc ngoai tai dinh B,C cat nhau tai K.Tia p/g goc B cat goc ngoai o dinh C.tinh cac goc BIC,BKC,BEC theo alpha.

tam giac ABC co goc A=90 do ve ra ngoai tam giac ABC cac tam giac deu ABD va ACE, BE cat CD tai I. CMR:

a)BE=CD

b)tam giac BDE can

c)goc EIC=60 do va IA la P/G cua goc DIE

cho tam giac abc co goc a bang 90 do. bd la phan giac cua goc b ve de vuong goc bc .goi f la giao diem cua ab va de 

a, chung mijh tam giac _{abd = tam giac ebd va duong trung truc cua ae}

_{b, chung minh tam giac dcf can}

_{c,  khi tam giac abc co goc b bang 60 do , c = 30 do va bc = 12 cm . tinh do dai dc}

cho tam giac ABC can tai A co gocA =80 do tren BC lay I saocho goc BAI=50 do tren AC lay K saocho goc ABK=30do hai doan AI va BKcat nhau tai H cm tam giac HIK can

Bai 1: Cho tam giac ABC nhon, duong cao BD, CE
a) CMR: tam giac ABD dong dang voi tam giac ACE
b) CMR: goc BED + goc BCD = 180 do
c) Cho goc BAC = 60 do; dien tich tam giac AED = 90 do . Tinh tam giac ABC