ko nho kien thuc lam :<

qua luoi :<

b, C1 = 60' ; F1 = 80'

c,co B1 = A = 90'(2 DT // )

nen B1 la goc vuong

d,110'

7A quyen gop dc 60 sach

7B quyen gop dc 72 sach

7C quyen gop dc 48 sach

a,51/20

b,7/13

c,23/12

dien tich xung quang cua can nha do la:

(6+4) x 2 x 3 = 60 m2

dien tich toan bo can nha do la:

60+(6x4x2)=108 m2

dien tich nha can phai son la:

108-(1x1)-(1,5x2)=104 m2

so tien cong anh Dong can phai tra la:

35000x104=3640000 dong

60' 30' 30'

b,vi DT EC cat hai DT BC va ED tai C va E va trong cac goc tao thanh co 1 cap goc so le trong bang nhau nen BC // ED (dau hieu nhan biet 2 DT song song)

c, xet tam giac ABC co goc A+B+C= 180' (DL tong 3 goc trong 1 tam giac

thay B=60,c=30 co

A+60+30=180

A=180-60-30

A=90'

co BAE + A = 180' (2 goc KB)

thay A = 90' co

BAE+90'=180'

BAE=90'

4 hop banh diana

x=1,41423

a,3/7

b,-2/3