Help with program involving Classes member functions

I'm suppose to create a program with a class with four members function to calculate the area of a triangle, square, hexagon, octagon with you enter the length of the side.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70



#include <iostream>
using namespace std;

class Area
{

private:

double L;

public:

Area(double L);
void SideLength();
void CalcAreaTriangle();
void CalcAreaSquare();
void CalcAreaHexagon();
void CalcAreaOctagon();

};

void Area::SideLength()
{
cout << "Enter the length of the side";
cin >> L;
}
void Area::CalcAreaTriangle()
{
cout << 0.433013*L*L;
}
void Area::CalcAreaSquare()
{
cout << L*L;
}
void Area::CalcAreaHexagon()
{
cout << 2.59808*L*L;
}
void Area::CalcAreaOctagon()
{
cout << 4.82843*L*L;
}

int main ()
{
double L;
Area CalcAreaTriangle(L);
Area CalcAreaSquare(L);
Area CalcAreaHexagon(L);
Area CalcAreaOctagon(L);




cout << "Area Trinagle = ";
CalcAreaTriangle(L);
cout << "Area Square = ";
CalcAreaSquare(L);
cout << "Area Hexagon = ";
CalcAreaHexagon(L);
cout << "Area Octagon = ";
CalcAreaOctagon(L);
cout << endl;


system ("pause");
return 0;
}