Bai 1: Hinh thang ABCD (AB//CD) co E la trung diem cua BC, goc AED=90 do. Chung minh rang DE la tia phan giac cua goc D.

Bai 2: Tim tu giac ABCD o cac cau sau la hinh thang biet:

a, Goc B=60 do, goc ngoai tai dinh A la 60 do

b, Goc A=150 do, Goc B=75 do

c, Goc C=115 do goc ngoai tai dinh D la 120 do

d, Goc ngoai tai dinh A la 95 do, goc ngoai tai dinh D la 85 do

GIUP MINH VOI! THANK YOU NHIEU !^^

Bai 1: Cho tam giac ABC vuong can tai A. Ve phia ngoai tam giac ABC, ve tam giac BCD vuong can tai B. Tu giac ABCD la hinh gi ? Vi sao?

Bai 2: Hinh thang vuong ABCD co goc A= goc D=90 do, AB=AD=2cm, DC= 4cm. Tinh cac goc cua hinh thang

Giup minh vs! Excuse me! Thank you rat nhieu !^^

cho tam giac ABC co BC=4cm. tren tia doi cua tia BC lay diem D sao cho BD=2cm/ a, tinh do dai CD; b,goi M la chung diem cua CD.tinh do dai BM;c,biet goc DAC bang 112 do .Ãxtia phan giac cua goc BAC va goc BAD. tinh so do goc xAy;d, tren nua mat phang bo la duong thang AC co chua diem D neu ve them n tia goc A phan biet khong trung voi cac tia ÂC,Ã,AB,Ay,AD thi co tat ca bao nhieu goc dinh A va Ay thu tu la

Hinh thang ABCD co AB//CD co E la trung diem cua BC goc AED= 90 do 

Chung Minh Rang DE la tia phan giac cua goc D

BAI 1 : cho hinh thang ABCD khong co goc vuong biet tong do dai 2 canh day AB va CD thi bang do dai canh ben AD cmr cac duong phan gaic trong goc A vs goc D di qua trung diem E cua BC

Bai 2 : cho hinh thang ABCD co AB//CD cmr neu CD = AD + BC thi cac duong phan giac cua cac goc A va B cat nhau tai 1 diem thuoc canh day CD 

Lam giup mink vs mink dang gap lam . THANKS

Cho hinh thang can ABCD (AB//CD) co DB la tia phan giac cua goc D ;DB vuong goc BC biet AB =4cm .Tinh chu vi hinh thang

1) Cho tu giac ABCD co AB=2,5cm; AD=4cm; BD=5cm; BC=8cm; CD=10cm. CMinh ABCD la hinh thang

3) Cho tam giac ABC co AB=4cm, D thuoc AC, AD=2cm, DC=6cm. Biet goc A=100, goc B-C=20. Tinh goc ABD

Cho tu giac ABCD biet so do cua cac goc A ,B,C,D ti le thuan voi5,8,13,10 .a, Tinh so do cac goc cua tu giac ABCD . b, Keo dai hai canh AB va DC cat nhau o E , keo dai hai canh AD va BC cat nhau o F . Hai tia phan giac cua cac goc AED va goc AFB cat nhau o O . phan giac cua goc AFB cat cac canh CD va AB tai M va N . Chung minh O la trung diem cua doan MN

CAC BAN GIUP MINH VOI MINH CAN GAP 

Bai 1: Cho hinh tam giac ABC co goc A = 90. Goi M la trung diem cua BC. Ke MN vuong goc voi
AB, MP vuong goc voi AC
a) Tu giac ABMP la hinh gi? Vi sao?
b) Tu giac ANMP la hinh gi? Vi sao'
) Tinh do dai doan NP biet BC = 8cm

d) Tam giac ABC can them dieu kien gi de ANMP la hinh vuong?