The Parabola tool allows you to create either an open or closed parabola in a few different ways. In an open parabola, the end points of the parabola are joined and the interior of the parabola is filled. For a closed parabola, the endpoints of the parabola are not connected and the interior is not filled. The second Option Button offers these construction methods:
- Vertical open
- Vertical closed
- Horizontal open
- Horizontal closed
The first option button determines the way the important points of the parabola are defined. The options are
- Vertex first and then drag to define the arc endpoints
- Arc endpoint first and then drag to define the vertex and second arc endpoint
- Define the distance between the arc endpoints on the side of the parabola away from the vertex and then drag to define the vertex
- Define the distance between the arc endpoints on the side of the parabola containing the vertex and then drag to define the arc endpoints
The last two options request the use of the mark button
to define the second point. Here’s an example of parabola construction: