-module(first). -export([double/1, treble/1, mult/2, square/1, area/3]). mult(X,Y) -> X*Y. double(X) -> mult(2,X). treble(X) -> mult(3,X). area(A,B,C) -> S = (A+B+C)/2, math:sqrt(S*(S-A)*(S-B)*(S-C)). square(X) -> mult(X, X).
