Returns shape points of an isosceles trapezoid. They can be used with xxx_extrude modules of dotSCAD. The shape points can be also used with the built-in polygon module.

## Parameters

`length`

: The base length of an isosceles trapezium. It also accepts a vector`[a, b]`

.`a`

is the bottom base and`b`

is the top base.`h`

: The height of the isosceles trapezium.`corner_r`

: The circle radius which fits the edges of the bottom and the top.`$fa`

,`$fs`

,`$fn`

: Used to control the corner fragments. Check the circle module for more details.

## Examples

```
include <shape_trapezium.scad>;
polygon(
shape_trapezium([40, 20],
h = 20,
corner_r = 2)
);
```

```
include <shape_trapezium.scad>;
include <rotate_p.scad>;
include <polysections.scad>;
include <path_extrude.scad>;
include <bezier_curve.scad>;
t_step = 0.05;
width = 2;
shape_pts = shape_trapezium(
[40, 20],
h = 20,
corner_r = 2
);
p0 = [0, 0, 0];
p1 = [40, 60, 35];
p2 = [-50, 70, 45];
p3 = [20, 150, 55];
p4 = [80, 50, 60];
path_pts = bezier_curve(t_step,
[p0, p1, p2, p3, p4]
);
path_extrude(shape_pts, path_pts);
```