Puzzle | Draw 4 straight line in 3*3 matrix (9 dots)

You have given 9 dots in the form of 2d matrix 3 * 3. Your task is to draw four straight lines without lifting the pen and no dot should be left untouched.
How will you solve this task?


Solution:
start from (A) upper corner of the right side to (B) bottom corner of the left side

and then B -> C extend some extra line from point C

then draw a line from C to D (here you understand the purpose of extended line)

and then draw new line from D to B.

In this way, you are able to draw 4 straight lines without lifting pen and visited all 9 dots.