def find_beamwidth(the_wavel,dish_size):
    """
    find the beamwidth using Stulll eq. 8.13
    
    Parameters
    ----------
    
    the_wavel : wavelength (float)
       units (cm)
            
    dish_size : antenna dish diameter (float)
       units (m)
       
    Returns
    -------
    
    beamwidth : beamwidth angle  
       units (degrees)
    """
    #
    # Stull eq. 8.13
    #
    ### BEGIN SOLUTION
    a = 71.6 #constant (degrees)
    the_wavel = the_wavel/100. #convert cm to m
    beamwidth = a*the_wavel/dish_size #beamwitdh in degrees
    return beamwidth
    ### END SOLUTION