second.erl

%first.erl:
treble(X) ->
    mult(3,X).
square(X) ->
    X*X.
%second.erl:
-module(second).
-export([hypotenuse/2,perimeter/2,area/2]).

hypotenuse(A,B) ->
   C = first:square(A) + first:square(B),
   math:sqrt(C).

perimeter(A,B) ->
   C = second:hypotenuse(A,B),
   A + B + C.

area(A,B) ->
   C = second:hypotenuse(A,B),
   first:area(A,B,C).