Question

若直线y-2=k（x-1）与圆x的平方+y的平方=1相切,则切线方程是

Answer 1

O:x^2+y^2=1

O(0,0),r=1

y-2=k*(x-1)

kx-y+2-k=0

|0-0+2-k|/√(1+k^2)=r=1

k=3/4

L1:x=1

L2:3x-4y+5=0