**This works as expected:**

```
BoundaryDiscretizeRegion[RegionUnion[Triangle[], Rectangle[{0.5, 0}, {1, 1}]]]

```

[![Union of triangle and rectangle](https://i.stack.imgur.com/ieAtom.jpg)](https://i.stack.imgur.com/ieAtom.jpg)

Now, suppose I want to change the fill color to green and the edge color to red. How would I do that?

*(I tried using RegionPlot, but that didn't work)*