TangentTo

Element

One of the two tangent lines to a conic or a circle through an external point. Construct the tangent line through a point to a conic or a circle. There will be either two, one or no such tangent, depending if the point is outside of the conic, on the conic, or inside of the conic. Similar to the intersection of a line with a circle, the specific tangent can be chosen with a third (optional) parameter number.

Attention: from a technical point of view, the point from which the tangent to the conic/circle is constructed is not an element of the tangent line.

Usage (signatures)
board.create('tangentto', [conic, point, numberopt]);

The result will be the tangent line through the point with respect to the conic or circle.

Parameters
Name Type Attributes Default Description
conic Conic | Circle
point Point
number Number <optional>
0
Examples
var c = board.create('circle', [[3, 0], [3, 4]]);
var p = board.create('point', [0, 6]);
var t0 = board.create('tangentto', [c, p, 0], { color: 'black', polar: {visible: true}, point: {visible: true} });
var t1 = board.create('tangentto', [c, p, 1], { color: 'black' });

var p = board.create('point', [0, 6]);
var ell = board.create('ellipse', [[-5, 1], [-2, -1], [-3, 2]]);
var t0 = board.create('tangentto', [ell, p, 0]);
var t1 = board.create('tangentto', [ell, p, 1]);

Attributes

Own

point

Description

Attributes for the intersection point of the conic/circle with the polar line of the tangentto construction.

Type
JXG.Point
Source
options.js, line 9776

polar

Description

Attributes for the polar line of the tangentto construction.

Type
JXG.Line
Source
options.js, line 9762

Inherited

Members

Own

point : JXG.Point

Description

The intersection point of the conic/circle with the polar line of the tangentto construction.

Type
JXG.Point
Source
base/line.js, line 3249

polar : JXG.Line

Description

The polar line of the tangentto construction.

Type
JXG.Line
Source
base/line.js, line 3257

Inherited

Methods

Own

none

Inherited

Events

Own

none

Inherited

Throws

If the element cannot be constructed with the given parent objects an exception is thrown.

Type
Exception

Details

Type
JXG.Line
Source
base/line.js, line 3150

Extends