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cho duong thang d va doan thang ab nam ngoai duong thang d , ve diem a' doi xung voi diem a qua d va diem b' doi xung voi siem b qua d , lay bdiem c thuoc doan thang ab , ve diem c' doi xung voi c qua d . chung minh ab=ab'
Cho tam giac ABC 2 duong trung tuyen BM,CN goi D la doi xung voi B qua M,, Ela doi xung voi C qua N
a)C/m ADCB la hinh binh hanh
b)C/m D,E doi xung nhau qua A
c) goi G la trong tam .Ke Bx // CG,Cy // BG :Bx cat Cy tai F C/m A doi xung F qua G
Cho 4 so duong a,b,c,d.CMR: a/b+c + b/c+d + c/a+d + d/a+b >=2
Cho cac so a,b,c,d duong va a.b.c.d=1 .CM
\(\left(a+b\right).\left(b+c\right).\left(c+d\right)\)\(.\left(d+a\right)\ge16\)
Cau 1: Cho tam giac ABC cuong tai A, AB8cm; AC15cm. Ve duong cao AHa) chung minh AB^2 BH. BCb) Tinh BH, CH, AH, BCc) Ve phan giac AD cua tam giac ABC. Chung minh H nam giua B va Dd) Tinh ti so dien tich D HAC va D A.BCCau 2: Cho tam giac ABC vuong tai A, AB5cm; Ac12cm, ve duong cao AH va duong phan giac AD.a) Tinh BC, BDb) Chung minh D ACH: D ABC; tinh AHc) Qua B ke duong thang vuong goc voi AB cat tia AD tai K. Chung minh AB.AD AC. KD.Cau 3: Cho tam giac ABC vuong A co AB 5cm; AC12cm. Ve dcao...
Đọc tiếp
Cau 1: Cho tam giac ABC cuong tai A, AB=8cm; AC=15cm. Ve duong cao AH
a) chung minh AB^2= BH. BC
b) Tinh BH, CH, AH, BC
c) Ve phan giac AD cua tam giac ABC. Chung minh H nam giua B va D
d) Tinh ti so dien tich D HAC va D A.BC
Cau 2: Cho tam giac ABC vuong tai A, AB=5cm; Ac=12cm, ve duong cao AH va duong phan giac AD.
a) Tinh BC, BD
b) Chung minh D ACH: D ABC; tinh AH
c) Qua B ke duong thang vuong goc voi AB cat tia AD tai K. Chung minh AB.AD =AC. KD
.Cau 3: Cho tam giac ABC vuong A co AB = 5cm; AC=12cm. Ve dcao AH va pgiac AD cua goc BAC
a) Tih BC; BD
b) Chung minh D HAC : D ABC
c) Qua B ke duong vgoc voi BA cat AD tai k. Chung minh AB.AD= AC.KD
Cho a,b,c thỏa mãn a^2+b^2+(a+b)^2=c^2+d^2+(c+d)^2. CM a^4+b^4+(a+b)^4=c^4+d^4+(c+d)^4
cho a b c d duong cm rang khong the dong thoi xay ra ca ba bat dang thuc
\(.a+b< c+d\)
\(.\left(a+b\right)\left(c+d\right)< ab+cd\)
\(.\left(a+b\right)cd< \left(c+d\right)ab\)
Cho tam giac ABC vuong tai A. AD la duong cao. Ke DH vuong goc voi AB. Goi DH=d,AB=c,AC=b. Chung minh rang: 1/d=1/b+1/c
Cho a,b,c,d khác 0 thỏa: a+b=c+d và a^2+b^2=c^2=d^2
Cm a^2016+b^2016=c^2016+d^2016