So, what im trying to do is get certain numbers from certain positions in a array of a given > range and put them into an equation

```
yy = arange(4)
xx = arange(5)
Area = ((xx[2] - xx[1])(yy[2] + yy[1])) / 2
```

I try to run it and I get this..

```
----> ((xx[2] - xx[1])(yy[2] + yy[1])) / 2
TypeError: 'numpy.int64' object is not callable
```

I get error.. how can I use certain numbers in an array and put them into an equation?