Menu Driven Program for Area of various figures in C++

#include<iostream.h>
#include<conio.h>
#include<process.h>
#include<math.h>
float area(float);
float area(float,float);
float area(float,float,float);
void main()
{
float a,b,c,s,ar;
int ch;
clrscr();
while(1)
{
cout<<"\nYou can chose from the following options:"<<endl;
cout<<"Press 1: Area of Square"<<endl;
cout<<"Press 2: Area of Rectangle"<<endl;
cout<<"Preaa 3: Area of Triangle"<<endl;
cout<<"Press 4: Exit"<<endl;
cout<<"Please Enter Your choice(1-4):";
cin>>ch;
switch (ch)
{
case 1:
cout<<"Please Enter the Side of the Square:";
cin>>a;
ar=area(a);
break;
case 2:
cout<<"Please enter the Length and Breadth of the Rectangle:";
cin>>a>>b;
ar=area(a,b);
break;
case 3:
cout<<"Please enter three sides of the Triangle:";
cin>>a>>b>>c;
ar=area(a,b,c);
break;
case 4:
exit(0);
default:
cout<<"Wrong Choice!! Please Enter the choice between 1 and 4"<<endl;
}
cout<<"Area of the given figure is: "<<ar;
cout<<"\nPreaa any key to continue...";
getch();
}
}
float area(float s)
{
return s*s;
}
float area(float l, float b)
{
return l*b;
}
float area(float a, float b, float c)
{
float s, ar;
s=(a+b+c)/2;
ar=sqrt(s*(s-a)*(s-b)*(s-c));
return ar;
}