-module(first).
-export([double/1,mult/2,area/3,square/1,treble/1]).

mult (X,Y)->
    X*Y.

double(X)->
    mult(2,X).

area(A,B,C)->
    S=(A+B+C)/2,
    math:sqrt(S*(S-A)*(S-B)*(S-C)).

square(A)-> % obtain the square of a number
    mult(A,A).

treble(A)-> % obtain the triple of a number
    mult(3,A).