from length import meter, centimeter, inch, foot, mile

#
# Definitions of common area units
# Data taken from Appendix F of Halliday, Resnick, Walker, "Fundamentals of Physics",
#     fourth edition, John Willey and Sons, 1993

square_meter = meter**2
square_centimeter = centimeter**2

square_foot = foot**2
square_inch = inch**2
square_mile = mile**2

acre = 43560 * square_foot
hectare = 1000 * square_meter

barn = 1e-28 * square_meter