Question

已知圆C的半径为2根号5,且与直线l:2x+y-6=0切于点T(1,4),求圆C的方程

Answer 1

k(CT)=-1/k(L)=1/2

CT:y-4=(1/2)*(x-1)

x=2y-7

C(2c-7,c)

CT^2=r^2

(2c-7-1)^2+(c-4)^2=(2√5)^2

c=0,8

C1(-7,0),C2(9,8)

C1:(x+7)^2+y^2=20

C2:(x-9)^2+(y-8)^2=20