# Python | Sympy Ellipse.tangent_lines method

• Last Updated : 30 Jan, 2020
In Sympy, the function `tangent_lines()` returns Tangent lines between p(point) and the ellipse.
If p is on the ellipse, returns the tangent line through point p. Otherwise, returns the tangent line(s) from p to the ellipse, or None if no tangent line is possible (e.g., p inside ellipse).
```Syntax: Ellipse.tangent_lines(p)

Parameter:
p:Point

Returns:
tangent_lines: list with 1 or 2 Lines or empty list

Raises:
NotImplementedError: Can only find tangent lines for a point, p, on the ellipse.
```

Example #1:

 `# import sympy and Point, Ellipse``from` `sympy ``import` `Point, Ellipse`` ` `# using Ellipse() method``e1 ``=` `Ellipse(Point(``0``, ``0``), ``3``, ``2``)`` ` `# using tangent_lines() method``l1 ``=` `e1.tangent_lines(Point(``3``, ``0``))`` ` `print``(l1)`

Output:

`[Line2D(Point2D(3, 0), Point2D(3, -12))]`

Example #2:

 `# import sympy and Point, Ellipse``from` `sympy ``import` `Point, Ellipse`` ` `# using Ellipse() method``e2 ``=` `Ellipse(Point(``0``, ``0``), ``3``, ``2``)`` ` `# using tangent_lines() method``l2 ``=` `e2.tangent_lines(Point(``1``, ``1``))`` ` `print``(l2)`

Output:

`[]`

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