I am trying to make a triangle, after updating to the latest Threejs.

Where I am making the geometry for the triangle, I can put:

```
var geometry=new THREE.BoxBufferGeometry(1000,1000,1000);
```

And then it draws a box perfectly.

But now I want to draw a triangle. So I googled triangle and wound up here:

https://threejs.org/docs/#api/en/math/Triangle

Going by that I comment the box way to make the geometry and replace it with the following:

```
var v1=new THREE.Vector3(0,1,0);
var v2=new THREE.Vector3(0,1,0);
var v3=new THREE.Vector3(0,1,0);
var geometry=new THREE.Triangle(v1, v2, v3);
```

But it gives me error:

```
Uncaught TypeError: can't convert undefined to object
```

But if I skip THREE, in THREE.triangle, I get

```
Uncaught ReferenceError: Triangle is not defined
```

How should one make the triangle geometry?

I realize I should go under the geometries section.

But there is no triangle geometry.