Question

过坐标原点且与圆x2加y2减4x加2y加5分之2等于0相切的直线方程为?

Answer 1

C:x^2+y^2-4x+2y+2/5=0

(x-2)^2+(y+1)^2=23/5

C(2,-1),r^2=23/5

kx-y=0

|2k+1|/√(1+k^2)=√(23/5)

k=(10±2√115)/3

y=[(10±2√115)/3]*x