HomeNon-Routine MathematicsRegions Made by Intersecting L...

Regions Made by Intersecting Lines

Logic, Pattern, and Formula for maximum number of regions that can be made by intersection of n lines in a plane.

Questions:

What is the maximum number of regions created by intersection of 5 lines in a plane?

How many regions (maximum) will 6 intersecting lines create in a plane ?


One line creates 2 regions in a plane (whichever way we draw it)
Total regions =2

2nd line creates 2 more regions in the plane when it intersects with the 1st line.

Total regions = 2+2=4

For creating maximum number of regions , point of intersection of each pair of lines should be different.

 

3rd line can create maximum 3 more regions in the plane when it intersects with the
existing 2 lines.
Total regions = 3+2+2=7

4th line can create maximum 4 more regions in the plane when it intersects with the
existing 3 lines.
Total regions = 4+3+2+2=11

Similarly,
5th line will create total = 5+4+3+2+2 = 16 regions
6th line will create total = 6+5+4+3+2+2 =22 regions

Hence, every nth line can create maximum n number of extra regions in a plane when it intersects with the existing (n-1) lines.

Hence n lines will create maximum      n+(n-1)+(n-2)……..3+2+2 regions
                                    =                                 n(n+1)      + 1 Regions
                                                                           2