(15C) Area and Perimeter of irregular polygon

[Werner]

Hi Marcel, yes that was an error, too.
But the formula you wrote (apart from the ||):

\(
Area = \frac{(x_{1}y_{2}-x_{2}y_{1})-(x_{2}y_{3}-x_{3}y_{2})- ..-(x_{n}y_{1}-x_{1}y_{n})}{2}
\)

That first term must be negative also, or just switch them all around

\(
Area = \frac{(x_{2}y_{1}-x_{1}y_{2})+(x_{3}y_{2}-x_{2}y_{3})+ ..+(x_{1}y_{n}-x_{n}y_{1})}{2}
\)

Cheers, Werner