import math


def distance_formula(x1: float, y1: float, x2: float, y2: float) -> float:
    """
    Distance between two points is defined as the square root of (x2 - x1)^2 + (y2 - y1) ^ 2

    :raises TypeError: Any of the values are non-numeric or None.
    """
    return math.sqrt(((x2 - x1) ** 2) + ((y2 - y1) ** 2))