howdy folks just one quick question here I put this simple function together and I everytime I try executing it I get some funky message saying unresolved external check it out

so where is the problem here.Code:

#include <iostream.h>

#include <ctype.h>

triangle(float a, float b);

void main()

{

float a,b;

float area;

cout<<char(22);

cout<<"Enter the length of the base of the triangle: "; cin>>a;

cout<<"Now enter the height: "; cin>>b;

triangle(a, b);

}

void triangle(float a, float b)

{

float area;

area = .5 * a * b;

cout<<"The area of the triangle is: "<<area;

}