'Are two or more of the sides the same length?
Returns
is_isosceles : boolean
See Also
is_equilateral, is_right, is_scalene
Examples
>>> from sympy.geometry import Triangle, Point
>>> t1 = Triangle(Point(0, 0), Point(4, 0), Point(2, 4))
>>> t1.is_isosceles()
True'

def is_isosceles(self):

    return has_dups((s.length for s in self.sides))
