Running two if statements in same function

I am trying to code a function where the given angle must be less than 90 degrees and greater than 0 degree. If the angle is in radians, it must be less than pi/2 and greater than 0.

This is my function:

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
    """
    if s[-1]=='r''R':
        if s < (pi/2):
            if s > 0:
                return true
    if s[-1]=='d''D':
            if s < 90:
                if s > 0:
                    return true

Also, I want to know if there's a way to shorten the two if statements, by using else.