If ```vecPR` = `vec2i` `+` `vecj` `+` `veck`, `vecQS` = `-` `veci` `+``vecj` `vecj` `+` 2`veck` then the area of the quadrilateral PQRS is
5`sqrt(3)`
10`sqrt(3)`
```(5sqrt(3))/(2)`
`3/2`
The QS vector does not have a co-efficient instead having a j vector again.