Perimeter = function (triangle)
{
    var line1 = triangle.getLineA();
    var line2 = triangle.getLineB();
    var line3 = triangle.getLineC();

    return (Length(line1) + Length(line2) + Length(line3));
}
Gets the length of the perimeter of the given triangle.
Calculated by adding together the length of each of the three sides.

@function Phaser.Geom.Triangle.Perimeter
@since 3.0.0

@param {Phaser.Geom.Triangle} triangle - The Triangle to get the length from.

@return {number} The length of the Triangle.