C++ programs please make me a program that will solve a trigonometry problem & also an array

Wruite a program that computes and assesses the tuition fee of the students in the third semester, based on the given mode of payment below...

Plan(key) Discount(-) or Interest(+)

cash(1) 10%discount
two-installment(2) 5%discount
three-installment(3) 10%interest

An array is a series of elements of the same type placed in contiguous memory locations that can be individually referenced by adding an index to a unique identifier
Initializing arrays. When declaring a regular array of local scope (within a function, for example), if we do not specify otherwise, its elements will not be initialized to any value by default, so their content will be undetermined until we store some value in them. The elements of global and static arrays, on the other hand, are automatically initialized with their default values, which for all fundamental types this means they are filled with zeros
include <iostream>
using namespace std;

int billy [] = {16, 2, 77, 40, 12071};
int n, result=0;

int main ()
{
for ( n=0 ; n<5 ; n++ )
{
result += billy[n];
}
cout << result;
return 0;
}
multidimensional array pseudo-multidimensional array #define WIDTH 5 #define HEIGHT 3 int jimmy [HEIGHT][WIDTH]; int n,m; int main () { for (n=0;n<HEIGHT;n++) for (m=0;m<WIDTH;m++) { jimmy[n][m]=(n+1)*(m+1); } return 0; } #define WIDTH 5 #define HEIGHT 3 int jimmy [HEIGHT * WIDTH]; int n,m; int main () { for (n=0;n<HEIGHT;n++) for (m=0;m<WIDTH;m++) { jimmy[n*WIDTH+m]=(n+1)*(m+1); } return 0; }
and now for trignometry
#include<iostream>
#include<cmath>
using namespace std;

int main()
{
int factorial(int);
int n = 3, i = 1;
double x, x2, b, PI, r;
char choice;
//r = x * (PI / 180)

cout<<"Please enter an angle value => ";
cin>>x;
cout<<"Is the angle value in Degree or Radian?"<<endl;
cout<<"Type D if its in degree "<<endl;
cout<<"Type R if its in radian "<<endl;
cin>>choice;


if((choice = 'R')||(choice = 'r'))
do{
i++; n = 3; x2 = 0; b = x2;
{
if(i == 1)
x2 = x - (pow(x,n) /factorial(n));
n = n + 2;
};
else
{
x2 = (x2 + ((pow(x,n)) /(factorial(n))) - (pow(x,n+2)) / (factorial(n+2)));
n = n + 4;
}


}while(abs(b - x2) > 0.000001);
else
//convert it to r

r = x * PI /180;

//cout<<"error occured/n";
cout<<"sin(x) = "<<x2<<endl;

return 0;
}