import math


def get_bounding_box(lat: float, lng: float, radius: float) -> str:
    """Get bounding box with length of radius * 2 and (lat, lng) as the centre"""
    offset = radius / 100.0
    latMax = lat + offset
    latMin = lat - offset

    lngOffset = offset * math.cos(lat * math.pi / 180.0)
    lngMax = lng + lngOffset
    lngMin = lng - lngOffset

    result = str(latMin) + "," + str(lngMin) + "," + str(latMax) + "," + str(lngMax)
    return result