cho a,b,c thoa man : a² + b² + c² = b² - c² / a²+3 + c²-a² / b² + 4 + a² -b²/ c² + 5 .

tinh gt cua bt P = 7a + 4b + 2019c

cho tam giac ABC vuong can tai A . lay M la trung diem cua BC , E la diem nam giua M va C ( E ko trung M va C ) . Ve BH vuong goc voi AE tai H , CK vuong goc voi AE tai K .

a CM: BH = AK

b CM: tam giac MHK vuong can

c Goi I la trung diem cua AH . CM : IM vuong goc voi BK

Cau a.b mk lam dc roi cac bn giup mk cau c nhe ! Cam on cac bn rat nhieu!Chuc cac bn hoc tot!

cho x, y la cac so nguyen duong sao cho A = x^4 + y^4 / 15 cung la so nguyen duong . cmr : x va y deu chia het cho 3 va 5 , tu do tim gtnn cua A

cho a+b / a- 3=b+4/b-4

tinh gt cua bieu thuc : D = a^3 +3^3 / b^3 +4^3

cho tam giac ABC vuong tai A ,co AC=2AB.lay D la trung diem cua AC .dung AH,CK vuong goc voii BC.

a) cm; goc ABC = goc CDK va tam giac AHB = tam giac CKD

b) cm : DA= DC =DH va KH = KC

c) goi I la trung diem cua BD . Cm: tam giac AHI = tam giac KHI tu do tinh soo do goc IHK

d ) duong thang di qua A song song voi BC cat DK tai M. cm : H , I , M thang hang

e) duong thang AI cat BC tai N . cm : NK =