The formula d you had used is to find the distance between the two parallel lines .
Distance will always be positive.
so even if C1-C2 is negative " I C1-C2 I is positive.
I -2 I = 2
I 2 I = 2
Hope it helps you
On Sunday, November 15, 2020 at 4:43:40 PM UTC+5:30 R wrote: