goi ptmp (P) can tim co dang: Ax+By+Cz+D=0
lay 2diem M,N thuoc d...toa do ro rang..ma dg thag d thuoc (P) nen M,N thuoc (P) nen ta co he pt........tu he viet duoc A,B theo C,D...khi do ptmp (P) co dang moi chi con 2 an...
ta lai co goc giua 2 mp =60....ta lap duoc pt nua theo cong thuc tinh goc giua 2mp..
=>ti C/D=.....
chon D=1 => C....
cuoi cung => ptmp (P) can tim
....tim giao diem cua (P) voi OZ thi:
OZ co pt: x=o va y=o
goi H la giao cua mp(P) voi OZ => toa do A la nghiem cua he:
x=0
y=0
ptmp (P)
.....=> toa do diem A can tim.......ok
co the a noi tn p hoi kho hieu nhung thong cam cho mjk nha...hj
kam on mk kau nha...

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