Question

圆内心在直线L:X-2Y-1=0上,并且经过原点和点A(2.1)求C标准方程

Answer 1

圆内心在直线L:X-2Y-1=0上,里面的a-2b=0错误,应该是a-2b-1=0

k(OA)=1/2

OA的中点M

xM=(xA+xO)=1,yM=1/2

M(1,1/2),k(CM)=-1/k(OA)=-2

CM:y-1/2=-2*(x-1)

4x+2y-5=0.(1)

L:x-2y-1=0.(2)

C(1.2,0.1)

r^2=CA^2=OC^2=1.2^2+0.1^2=1.45

(x-1.2)^2+(y-0.1)^2=1.45