xet ngu giac
ABCND co
^BAD=^BCD=^BND=900=>ngu giac nay noi tiep duong tron duong kinh BD tam
I la trung diem
BD va
AC goi C(a;−5−2a)=>I(a−42;3−2a2) ma IA=IN=>(a+4)2+(15+2a)2=(a−14)2+(11−2a)2
=>a=76140 (so xau nen ban tu tinh nha)=>C;I
goi B theo hai an thuoc duong tron tam I(co mot pt )
=> toa do cua M,D =>M,N.D thang hang (pt thu hai)(khong can dung BN vuong goc voi DM vi da sd o tren)
tu hai pt => toa do cua B