Hi people,

I'm currently trying to find a formula for calculating an Area of Cross/Plus Shape

It looks like this : +

It has 12 sides (12 coordinates)

For example

1,2

2,2

2,1

3,1

3,2

4,2

4,3

3,3

3,4

2,4

2,3

1,3

I've tried using this formula:

Area of any polygon (Coordinate Geometry) - Math Open Reference

The expected answer should be 5, but I got 4 instead.

Is there actually a formula for this?