diff --git a/CTDL-GT/Test1_L02.cpp b/CTDL-GT/Test1_L02.cpp
new file mode 100644
index 0000000..e3d4a77
--- /dev/null
+++ b/CTDL-GT/Test1_L02.cpp
@@ -0,0 +1,281 @@
+#include <cmath>
+#include <iostream>
+
+using namespace std;
+
+#define EPSILON 1E-10
+
+struct Point {
+    double x;
+    double y;
+    string name;
+    Point *next;
+    Point()
+    {
+        this->x = 0;
+        this->y = 0;
+        this->name = "";
+        this->next = nullptr;
+    }
+    Point(Point *p)
+    {
+        this->x = p->x;
+        this->y = p->y;
+        this->name = p->name;
+        this->next = nullptr;
+    }
+    Point(double x, double y, string name)
+    {
+        this->x = x;
+        this->y = y;
+        this->name = name;
+        this->next = nullptr;
+    }
+};
+
+void appendPoint(Point *&pHead, Point *newPoint)
+{
+    if (pHead == nullptr) {
+        pHead = newPoint;
+        return;
+    }
+    Point *temp = pHead;
+    while (temp->next != nullptr)
+        temp = temp->next;
+    temp->next = newPoint;
+}
+
+double distancePointToLine(Point *point, double a, double b, double c)
+{
+    if (point == nullptr)
+        return -1;
+    return abs(a * point->x + b * point->y + c) / sqrt(a * a + b * b);
+}
+
+Point *listPoint(Point *pHead, double a, double b, double c, double H)
+{
+    Point *newList = nullptr;
+    Point *temp = pHead;
+    while (temp != nullptr) {
+        if (distancePointToLine(temp, a, b, c) >= H) {
+            Point *newPoint = new Point(temp);
+            appendPoint(newList, newPoint);
+        }
+        temp = temp->next;
+    }
+    return newList;
+}
+
+double distanceBetweenTwoPoint(Point *point1, Point *point2)
+{
+    if (point1 == nullptr || point2 == nullptr)
+        return -1;
+    return sqrt(pow(point1->x - point2->x, 2) + pow(point1->y - point2->y, 2));
+}
+
+void printLineFromTwoPoint(Point *point1, Point *point2)
+{
+    if (point1 == nullptr || point2 == nullptr) {
+        cout << "Diem 1 hoac diem 2 chua xac dinh!" << endl;
+        return;
+    }
+    if (distanceBetweenTwoPoint(point1, point2) < EPSILON) {
+        cout << "Hai diem da cho trung nhau!" << endl;
+        return;
+    }
+    double a = (point1->y - point2->y);
+    double b = (point2->x - point1->x);
+    double c = a * (-point1->x) + b * (-point1->y);
+    cout << a << " * x + " << b << " * y + " << c << " = 0" << endl;
+}
+
+void printAllLineFromPointList(Point *pHead)
+{
+    if (pHead == nullptr)
+        return;
+    Point *temp = pHead->next;
+    while (temp != nullptr) {
+        printLineFromTwoPoint(pHead, temp);
+        temp = temp->next;
+    }
+    printAllLineFromPointList(pHead->next);
+}
+
+void prependPoint(Point *&pHead, Point *&newPoint)
+{
+    newPoint->next = pHead;
+    pHead = newPoint;
+}
+
+Point *findPreMinPoint(Point *pHead, double a, double b, double c)
+{
+    if (pHead == nullptr)
+        return nullptr;
+    Point *preMinPoint = nullptr;
+    double minLenght = distancePointToLine(pHead, a, b, c);
+    Point *temp = pHead;
+    while (temp->next != nullptr) {
+        double distance = distancePointToLine(temp->next, a, b, c);
+        if (distance < minLenght) {
+            minLenght = distance;
+            preMinPoint = temp;
+        }
+        temp = temp->next;
+    }
+    return preMinPoint;
+}
+
+void sortDecreaseDistanceToLine(Point *&pHead, double a, double b, double c)
+{
+    if (pHead == nullptr)
+        return;
+    if (pHead->next == nullptr)
+        return;
+    Point *sortedList = nullptr;
+    while (pHead != nullptr) {
+        Point *temp = nullptr;
+        Point *preMinPoint = findPreMinPoint(pHead, a, b, c);
+        if (preMinPoint == nullptr) {
+            temp = pHead;
+            pHead = pHead->next;
+        } else {
+            temp = preMinPoint->next;
+            preMinPoint->next = temp->next;
+        }
+        prependPoint(sortedList, temp);
+    }
+    pHead = sortedList;
+}
+
+double sumAllDistanceToLine(Point *pHead, double a, double b, double c)
+{
+    if (pHead == nullptr)
+        return 0;
+    return distancePointToLine(pHead, a, b, c) + sumAllDistanceToLine(pHead->next, a, b, c);
+}
+
+bool isCyclicQuadrilateral(Point *a, Point *b, Point *c, Point *d)
+{
+    double ab = distanceBetweenTwoPoint(a, b);
+    double ac = distanceBetweenTwoPoint(a, c);
+    double ad = distanceBetweenTwoPoint(a, d);
+    double bc = distanceBetweenTwoPoint(b, c);
+    double bd = distanceBetweenTwoPoint(b, d);
+    double cd = distanceBetweenTwoPoint(c, d);
+    if (ab < EPSILON || ac < EPSILON || ad < EPSILON || bc < EPSILON || bd < EPSILON || cd < EPSILON)
+        return false;
+    double cosA = (ab * ab + ad * ad - bd * bd) / (2 * ab * ad);
+    double cosC = (bc * bc + cd * cd - bd * bd) / (2 * bc * cd);
+    if (abs(cosA + cosC) > EPSILON || abs(abs(cosA) - 1) < EPSILON || abs(abs(cosC) - 1) < EPSILON)
+        return false;
+    return true;
+}
+
+bool checkAndPrintCyclicQuadrilateral(Point *a, Point *b, Point *c, Point *d)
+{
+    bool check = isCyclicQuadrilateral(a, b, c, d);
+    if (check) {
+        cout << a->name << " " << b->name << " " << c->name << " " << d->name << endl;
+        return true;
+    }
+    return false;
+}
+
+void printAllCyclicQuadrilateral(Point *pHead)
+{
+    Point *a = pHead;
+    while (a != nullptr) {
+        Point *b = a->next;
+        while (b != nullptr) {
+            Point *c = b->next;
+            while (c != nullptr) {
+                Point *d = c->next;
+                while (d != nullptr) {
+                    if (checkAndPrintCyclicQuadrilateral(a, b, c, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(a, b, d, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(a, c, b, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(a, c, d, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(a, d, b, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(a, d, c, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, a, c, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, a, d, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, c, a, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, c, d, a)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, d, a, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(b, d, c, a)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, a, b, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, a, d, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, b, a, d)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, b, d, a)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, d, a, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(c, d, b, a)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, a, b, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, a, c, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, b, a, c)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, b, c, a)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, c, a, b)) {
+                    } else if (checkAndPrintCyclicQuadrilateral(d, c, b, a)) {
+                    }
+                    d = d->next;
+                }
+                c = c->next;
+            }
+            b = b->next;
+        }
+        a = a->next;
+    }
+}
+
+void printAllPointInList(Point *pHead)
+{
+    Point *temp = pHead;
+    while (temp != nullptr) {
+        cout << temp->name << " " << temp->x << " " << temp->y << endl;
+        temp = temp->next;
+    }
+}
+
+void clearPointList(Point *&pHead)
+{
+    while (pHead != nullptr) {
+        Point *temp = pHead;
+        pHead = pHead->next;
+        delete temp;
+    }
+}
+
+int main()
+{
+    Point *pHead = nullptr;
+    double x[] = {
+        2, 4, 6, 2, 4, 6, 2, 4, 6
+    };
+    double y[] = {
+        1, 1, 1, 3, 3, 3, 5, 5, 5
+    };
+    string name[] = {
+        "A", "B", "C", "D", "E", "F", "G", "H", "I"
+    };
+    for (int i = 0; i < 3; ++i) {
+        for (int j = 0; j < 3; ++j) {
+            Point *newPoint = new Point(x[i * 3 + j], y[i * 3 + j], name[i * 3 + j]);
+            cout << distancePointToLine(newPoint, 1, 0, 0) << endl;
+            prependPoint(pHead, newPoint);
+        }
+    }
+    printAllPointInList(pHead);
+    clearPointList(pHead);
+    for (int i = 0; i < 3; ++i) {
+        for (int j = 0; j < 3; ++j) {
+            Point *newPoint = new Point(x[i * 3 + j], y[i * 3 + j], name[i * 3 + j]);
+            cout << distancePointToLine(newPoint, 0, 1, 0) << endl;
+            appendPoint(pHead, newPoint);
+        }
+    }
+    printAllPointInList(pHead);
+    sortDecreaseDistanceToLine(pHead, 1, -1, 0);
+    printAllPointInList(pHead);
+    printAllLineFromPointList(pHead);
+    printAllCyclicQuadrilateral(pHead);
+    return 0;
+}