import math
g = 9.81
pi = math.pi


def is_valid_angle(s:str)-> bool: <
    """
    Returns True if and only if s is a valid angle. See the assignment
    description and examples for more information regarding what's valid

    Examples:
    >>> is_valid_angle("85.3d")
    True
    >>> is_valid_angle("85.3.7D")
    False
    >>> is_valid_angle("90d")
    False
    >>> is_valid_angle("0.001r")
    True
    >>> is_valid_angle("1.5R")
    True
    """
    #Your code goes here

    if 'd' or 'D' in is_valid_angle:
        newstr = is_valid_angle.replace("r", "")
        newstr = is_valid_angle.replace("R", "")
        if float(90) >= float(newstr) <= float(0):
            return "True"
        if 90 <= float(newstr) >= 0:
            return "False"

    if 'r' or 'R' in is_valid_angle:
        newstr = is_valid_angle.replace("D", "")
        newstr = is_valid_angle.replace("d","")
        if (float(pi/2)) >= float(newstr) <= float(0):
            return "True"
        if float((pi/2)) <= float(newstr) >= float(0):
            return "False"