User question:
user: I'm working on some land survey data and need to calculate the area of a particular triangular plot. I've got the coordinates of the vertices of the triangle, which are (1,2), (3,4), and (1,3). Can you help me figure out the area of this triangle using these points?

Available functions:
name: polygon_area
description: Calculate the area of a polygon given its vertices using the shoelace formula.
parameters: type: dict
properties: vertices: type: array
items: type: array
items: type: integer
description: A single vertex represented by a 2 element list [x, y].
description: The vertices of the polygon, where each vertex is a 2 element list [x, y].
required: vertices

Ground-truth function call(s):
polygon_area(vertices=[[1,2],[3,4],[1,3]])