Chứng minh a/a-b=c/c-d biết a/b=c/dCho ab=cd chứng minh rằng:a) aa−b =cc−db) ab=a+cb+dc)a3a+b=c3c+bd) a.cb.c=a2+c2b2+d2e) a.bc.d=a2−b2c2−d2f) a.bc.d=(a−b)2(c−d)2
cho tam giac abc, tren nua mat phang bo ac k chua diem b ke ax vuong goc ab,cy vuon goc cb,ax cat cb tai d
a, chung minh ad=cd
b, goi e la giao diem cua ab va bd. chung minh ea=ec
c, tinh ac biet ab=7cm,be=5cm
d,goi m la trung diem cua bc,am cat be tai g. chung minh ah=2gm
Chung minh rang a/b=c/d thi a2+b2/c2+d2=ab/d
cho a/b=c/d Chung minh a^2+b^2 / a^2 -b^2 = c^2+d^2 /c^2 -d^2
Cho a/b=c/d chung minh a)ac/bc=a2+c2/b2+d2
b)ab/cd=a2-b2/c2-d2
c)ab/cd=(a-b)2/(c-d)2
CHo ti le thuc a/b=c/d Chung minh rang (a+b/c+d)^2=a^2+b^2/c^2+d^2
cho 4 so a,b,c,d sao cho a.c=b^2,b.d=c^2. chung minh a/d=a^2+b^2+c^2/b^2+c^2+d^2
CHO A/B=C/D CHUNG MINH
A^2-B^2/C^2-D^2 =AB/CD
(A-B)^2/(C-D)^2=AB/CD
Cho hai đoan thang ABvaCD cat nhau tai trung điem ocuar moi doan thang. Hoi
a chung minh AC = DB va AC //DB
b chung minh AD = CB va AD// CB
c chung minh goc ACB = goc BDA
d ve CH vuong goc AB tai H . Tren tia doi OH lay diem I sao cho OI = OH . Chung minh O la trung diem EF
