SlopeTriangle

Creates slope triangle which displays the slope based on a point on a line. The parameter are a line and a glider which can be passed in through composing elements [eLine, eGlider]. You can also pass in a tangent as a parameter [eTangent].

```graph
bounds: [-10, 10, 10, -10]
elements: [
	{type: line, def: [[0,0], [2,5]]},
	{type: glider, def: [0, 0, e0]},
	{type: slopetriangle, def: [e0, e1]}
]
```

```graph
bounds: [-10, 10, 10, -10]
elements: [
	{type: functiongraph, def: [f:sin(x)]},
	{type: glider, def: [0, 0, e0]},
	{type: tangent, def: [e1]},
	{type: slopetriangle, def: [e2]}
]
```