Bai_3_calculcus

AdvProg_L2-Calculus/calculus.cpp

@@ -2,11 +2,10 @@
 #include <string>
 #include <cmath>
 
-using std::string;
 using std::cout;
 using std::endl;
 using std::stod;
-
+using std::string;
 
 double mySin(double x);
 double myCos(double x);
@@ -18,9 +17,10 @@ double mySqrt(double x);
     Returns:
         double: cosine of x
 ***/
-double myCos(double x) 
+double myCos(double x)
 {
-    return 0.0;
+    double ket_qua = 1 - pow(x, 2) / 2 + pow(x, 4) / 24 - pow(x, 6) / 720;
+    return ket_qua;
 }
 
 /***
@@ -31,22 +31,30 @@ double myCos(double x)
 ***/
 double mySin(double x)
 {
-    return 0.0;
+    double ket_qua = x - pow(x, 3) / 6 + pow(x, 5) / 120 - pow(x, 7) / 5040;
+    return ket_qua;
 }
 
-
 /***
     Args:
         x (double): a number
     Returns:
         double: square root of x
 ***/
-double mySqrt(double x) {
-    if (x < 0) {
+double mySqrt(double x)
+{
+    if (x < 0)
+    {
         cout << "Invalid argument" << endl;
         exit(1);
     }
-
-
-    return 0;
+    else
+    {
+        double ket_qua = x;
+        for (int i = 0; i < 5; i++)
+        {
+            ket_qua = (ket_qua + x / ket_qua) / 2;
+        }
+        return ket_qua;
+    }
 }