The number of circles that touch all the three lines $x+y-1=0, x-y-1=0$ and $y+1=0$ is
The number of circles that touch all the three lines $x+y-1=0, x-y-1=0$ and $y+1=0$ is
$2$
$3$
$4$
$1$
Solution
Given lines are
$
x+y-1=0, x-y-1=0 \text { and } y+1=0
$
These lines form a triangle the total number of circles that touches all the three sides of a triangle are 4.
$[\because$ One is incircle of a triangle and when we extend the sides of a triangle we will get the three ex-circle which touches all sides of a triangle]