Calculator, Includes Sin, Cos, Tan And Sqaure Root!

#include <iostream>
#include <conio.h>
#include <math.h>
#include <stdio.h>

using namespace std;

#define PI 3.14159265

int main()
{
    system("TITLE My Calculator Program.");
    system("COLOR C");
    
    
    double firstNumber, secondNumber;
    double resultSqrt, resultSin, resultCos, resultTan;
    char operation, boolSqrt; 
    
    cout << " *****************************************" << endl;;
    cout << "  Kizzop Productions - Simple Calculator!" << endl;;
    cout << " *****************************************\n\n"; 
    
    cout << "  OPERATORS : +, -, *, /, !, S, C, T" << endl;
    cout << " \n";
    
    cout << "  + = ADD\n  - = SUBTRACT\n  * = Multiplication\n  ";
    cout << "/ = Division\n  ! = SQAURE ROOT\n  S = SIN\n  ";
    cout << "C = COS\n  T = TAN\n";
    
    cout << " \n ************************************************" << endl;
    cout << "  NOTE : YOU CAN USE X AND x FOR MULTIPLICATION!" << endl;
    cout << " ************************************************\n\n";    
       
    cout << "\n ENTER FIRST NUMBER  : ";
    cin  >> firstNumber;

    cout << "\n ENTER OPERATOR SIGN : ";
    cin  >> operation;
    
    resultSqrt = sqrt (firstNumber);
    
    resultSin = sin (firstNumber*PI/180);
    
    resultCos = cos (firstNumber*PI/180);
    
    resultTan = tan (firstNumber*PI/180);
    
         switch(operation)
         {
                          case '+':
                          cout << "\n ENTER SECOND NUMBER : ";
                          cin  >> secondNumber;
                          cout << "\n Answer = " << (firstNumber + secondNumber);
                          break;
                          
                          case '-':
                               cout << "\n ENTER SECOND NUMBER : ";
                          cin  >> secondNumber;
                          cout << "\n Answer = " << (firstNumber - secondNumber);
                          break;
                          
                          case '*':
                          case 'x':
                          case 'X':
                          cout << "\n ENTER SECOND NUMBER : ";
                          cin  >> secondNumber;
                          cout << "\n Answer = " << (firstNumber * secondNumber);
                          break;
                          
                          case '/':
                          cout << "\n ENTER SECOND NUMBER : ";
                          cin  >> secondNumber;
                          cout << "\n Answer = " << (firstNumber / secondNumber);
                          break;
                          
                          case '!':
                          cout << "\n ANSWER = " << resultSqrt;
                          break;
                          
                          case 'S':
                          case 's':
                          cout << "\n ANSWER = " << resultSin;
                          break;
                          
                          case 'C':
                          case 'c':
                          cout << "\n ANSWER = " << resultCos;
                          break;
                          
                          case 'T':
                          case 't':
                          cout << "\n ANSWER = " << resultTan;
                          break;
                          
                          default:
                          cout << "\n WRONG MATHMATICAL OPERATOR!";
                          break;
                          
         }
                          system("PAUSE > nul");
         }