R
ronaldo97_9x


trong mat phang he truc toa do OXY cho duong tron (C) co pt
X-1)^2+(Y+2)^2=9 va duong thang d:X+Y+m=0.tim m de tren duong thang d ke duoc 2 tiep tuyen AB,AC toi (C) sao cho tam giac ABC vuong