cho hinh ve biet goc a1=5/7goc a2, goc b2- goc b1=30 do va a vuong goc c tinh goc c1 va goc c2
cho a//b ;c//d; goc B2=125 do
Hoi goc C1=? ;goc A1=?
goc D2=?;goc A2=?
GOCD4=?; goc C4=?
a vuông góc d,b vuong goc d và A1-B1=40°
a,chứng minh a//b
b, tính số đo A2 và B2
a) duong thang c co vuong goc voi duong thang b ko vi sao
b)cho doan thang d cat 2 duong thang a va b tai A va B cho niet goc A1= 115do . Tinh so do cac goc B2,B3,A3
c)goi AX va By lan luot la tia phan giac cua cac goc A1 va B CHUNG MINH Ax song song By
cho goc nhon xOy. diem h nam tren tia phan giac Oz cua goc xOy . tu h dung duong HA vuong goc Oy;HB vuong goc Oy (a thuoc Ox, B thuoc Oy )
a) chung minh : tam giac HAO= tam giac HBO
b) chung minh: goc OAB bang goc OBA
c) goi D la hinh chieu cua diem A tren Oy, C la giao diem cua AD voi OH . chung minh BC vuong goc Ox
d)neu goc xOy co do bang 60 do . hay chung minh OD=1/2OA
cho tam giac ABC co goc A - goc B = 90 do . tu goc C ke CH vuong goc voi AB . Chung minh goc HAC = goc BCH
cho tam giac ABC co goc C nho nhat. Tu B ve 1 duong thang song song voi phan giac AD cua goc BAC, duong nay cat AC tai E .
a) Chung minh goc BAC la goc nhon
b) Chung minh tam giac ABE co 2 goc bang nhau
c)Goi M la trung diem BE. Chung minh tam giac AMB=tam giac AME va AM vuong goc voi BE
d)Ke BH vuong goc voi AC, O la giao diem cua AD voi BH biet goc A=2 goc B. Tinh goc HOD
cho tam giac ABC ,O la diem nam trong tam giac
a)chung minh rang goc BOC=goc A+ goc ABO+ goc ACO
b) biet goc ABO+ goc ACO= 90 -A/2 va tia BO la tia phan giac cua goc B chung minh rang tia CO l tia phan giac cua goc C
ai giup minh vs bay ruoi minh on minh tick cho
Cho tam giac ABC co goc B>goc C duong thang chua tia phan giac goc ngoai dinh A cat duong thang BC o E.CM goc AEB=1/2.(goc B-goc C)
Cac ban co gang giup do. Neu co ai muon thay hinh anh cua minh thi len facbook nhan Le Dinh LUC