我有一个有4个角的多边形，而不是正方形。如何在python中获得较小部分的纬度和经度？

import math

# 多边形的坐标点
polygon = [(lat1, lon1), (lat2, lon2), (lat3, lon3), (lat4, lon4)]

# 计算多边形的中心点坐标
center_lat = sum(lat for lat, _ in polygon) / len(polygon)
center_lon = sum(lon for _, lon in polygon) / len(polygon)

# 计算多边形的边长
side_length = math.dist(polygon[0], polygon[1])

# 计算较小部分的纬度和经度
small_part_lat = center_lat - side_length / 2
small_part_lon = center_lon - side_length / 2

print("较小部分的纬度:", small_part_lat)
print("较小部分的经度:", small_part_lon)