Cosine Calculator

#include <iostream>
#include <cmath>
#include <climits>
#include <iomanip>

using namespace std;

double Cos(double);
double Fact(int);
double ConvertTo(double);

int main()
{
    double degrees;
    cin >> degrees;

    if(degrees > 180)
    {
        degrees = ConvertTo(degrees);
    }

    if(degrees < 0)
    {
        degrees = degrees*(-1);
    }

    double radians = (degrees/180)*3.14159;

    cout << setprecision(7) << Cos(radians) << endl;
}

double Cos(double number)
{
    double cos = 0;

    cout << fixed;
    for(int i = 0; i <= 18; i++)
    {
        cos += (pow(-1,i)*pow(number,(2*i)))/Fact(2*i);
    }

    return cos;
}

double Fact(int num) //factorial algorithm
{
    double counter = 1;

    for(double i = 1; i <= num; i++)
    {
        counter = counter * i;

        if(counter >= INT_MAX)
        {
           break;
        }
    }

    return counter;
}

double ConvertTo(double number) //converts degrees to radians
{
    int num = number/180.0;
    number = number - (int)(num*180);
    number = (double)number;

    return number;
}

/*
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Calculus II Math Exercise - Degrees to Arc Length
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*/