diff --git a/Exercises_13_1-2-11.cpp b/Exercises_13_1-2-11.cpp
new file mode 100644
index 0000000..4947ca1
--- /dev/null
+++ b/Exercises_13_1-2-11.cpp
@@ -0,0 +1,142 @@
+//Exercises_9_4.cpp Exercises at end of Chapter 9
+
+#include <opencv2/opencv.hpp>
+#include <iostream>
+
+using namespace cv;
+using namespace std;
+
+void help(const char **argv) {
+	cout << "\n\n"
+		<< "This program solves the Exercise 4、5 at the end of Chapter 9 \n"
+		<< "Call:\n"
+		<< argv[0] << " <path/image_name1>" << " <path/image_name2>\n\n"
+		<< "For example: ./" << argv[0] << " ../left.jpg "<< " ../left.jpg\n"
+		<< endl;
+}
+
+int main( int argc, const char** argv )
+{
+  help(argv);
+	if(argc < 3) {
+		cout << "\nERROR: You had too few parameters.\n" << endl;
+		return -1;
+	}
+
+	/************************************************************************/
+	/* 1.In  this  exercise,  we  learn  to  experiment  with  parameters  by  setting  good  low
+	Thresh  and  highThresh  values  in  cv::Canny().  Load  an  image  with  suitably
+	interesting line structures. We’ll use three different high:low threshold settings of
+	1.5:1, 2.75:1, and 4:1.
+	a.  Report what you see with a high setting of less than 50.
+	b.  Report what you see with high settings between 50 and 100.
+	c.  Report what you see with high settings between 100 and 150.
+	d.  Report what you see with high settings between 150 and 200.
+	e.  Report what you see with high settings between 200 and 250.
+	f.  Summarize your results and explain what happens as best you can.                                                                     */
+	/************************************************************************/
+  Mat src = imread(argv[1],IMREAD_GRAYSCALE);
+	Mat dst;
+	
+	int iHighThresh = 50;
+	Canny(src,dst,static_cast<int>(iHighThresh/1.5),iHighThresh);
+	imshow("iHighThresh is 50 and  high:low is 1.5:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/2.75),iHighThresh);
+	imshow("iHighThresh is 50 and  high:low is 2.75:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/4),iHighThresh);
+	imshow("iHighThresh is 50 and  high:low is 4:1",dst);
+
+	iHighThresh = (50+100)/2;
+	Canny(src,dst,static_cast<int>(iHighThresh/1.5),iHighThresh);
+	imshow("iHighThresh is (50+100)/2 and  high:low is 1.5:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/2.75),iHighThresh);
+	imshow("iHighThresh is (50+100)/2 and  high:low is 2.75:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/4),iHighThresh);
+	imshow("iHighThresh is (50+100)/2 and  high:low is 4:1",dst);
+
+	iHighThresh = (100+150)/2;
+	Canny(src,dst,static_cast<int>(iHighThresh/1.5),iHighThresh);
+	imshow("iHighThresh is (100+150)/2 and  high:low is 1.5:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/2.75),iHighThresh);
+	imshow("iHighThresh is (100+150)/2 and  high:low is 2.75:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/4),iHighThresh);
+	imshow("iHighThresh is (100+150)/2 and  high:low is 4:1",dst);
+
+	iHighThresh = (150+200)/2;
+	Canny(src,dst,static_cast<int>(iHighThresh/1.5),iHighThresh);
+	imshow("iHighThresh is (150+200)/2 and  high:low is 1.5:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/2.75),iHighThresh);
+	imshow("iHighThresh is (150+200)/2 and  high:low is 2.75:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/4),iHighThresh);
+	imshow("iHighThresh is (150+200)/2 and  high:low is 4:1",dst);
+
+	iHighThresh = (200+250)/2;
+	Canny(src,dst,static_cast<int>(iHighThresh/1.5),iHighThresh);
+	imshow("iHighThresh is (200+250)/2 and  high:low is 1.5:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/2.75),iHighThresh);
+	imshow("iHighThresh is (200+250)/2 and  high:low is 2.75:1",dst);
+	Canny(src,dst,static_cast<int>(iHighThresh/4),iHighThresh);
+	imshow("iHighThresh is (200+250)/2 and  high:low is 4:1",dst);
+
+	/************************************************************************/
+	/* 2.  Load an image containing clear lines and circles such as a side view of a bicycle.
+	Use  the  Hough  line  and  Hough  circle  calls  and  see  how  they  respond  to  your
+	image.                                                                     */
+	/************************************************************************/
+	Mat src = imread(argv[1],IMREAD_GRAYSCALE);//a bike in gray
+	GaussianBlur( src, src, Size(9, 9), 2, 2 );
+	Mat temp;
+	vector<Vec4i> linesP;
+	vector<Vec3f> circles;
+	//first find the canny edge
+	Canny(src,temp,50,200);
+	//find lines
+	HoughLinesP(temp,linesP,1,CV_PI/180,80,50,10);
+	//find circles
+	HoughCircles( src, circles, CV_HOUGH_GRADIENT, 1, src.rows/8, 200, 100, 0, 0 );
+	//draw lines and circles in the source image
+	for (int i = 0;i<linesP.size();i++)
+	{
+		Vec4i l = linesP[i];
+		line(src,Point(l[0],l[1]),Point(l[2],l[3]),Scalar(255));
+	}
+
+	for( size_t i = 0; i < circles.size(); i++ )
+	{
+		Point center(cvRound(circles[i][0]), cvRound(circles[i][1]));
+		int radius = cvRound(circles[i][2]);
+		// circle center
+		circle( src, center, 3, Scalar(255,255,255), -1, 8, 0 );
+		// circle outline
+		circle( src, center, radius, Scalar(255,255,255), 1, 8, 0 );
+	}
+	
+	/*11.  Create an image with a 20 × 20 square in it. Rotate it to an arbitrary angle. Take a
+	distance transform of this image. Create a 20 × 20 square shape. Use the distance
+	transform image to algorithmically overlay the shape onto the rotated square in
+	the image you made.*/
+	// create a 20 × 20 square
+	Mat matBoard = Mat(500,500,CV_8UC3,Scalar(0));
+	rectangle(matBoard,Rect(250,250,20,20),Scalar(255,255,255),-1);
+	// create an arbitary angle
+	cv::RNG rng = cv::theRNG();
+	float fDegree = rng.uniform(0,360);
+	Mat rotMatS = getRotationMatrix2D(Point(250,250), fDegree, 1.0);
+	warpAffine(matBoard, matBoard, rotMatS, matBoard.size(), 1, 0, Scalar(0,0,0));
+	//solove the problem
+	Mat matDistance;
+	cvtColor(matBoard,gray,COLOR_BGR2GRAY);
+	threshold(gray,gray,100,255,CV_THRESH_BINARY); 
+	distanceTransform(gray,matDistance,CV_DIST_L2,3);  
+       //find the center corners
+	double minVal; 
+	double maxVal2; 
+	Point minLoc,maxLoc;
+	minMaxLoc( matDistance, &minVal, &maxVal2, &minLoc, &maxLoc, matDistance>0); 
+	//draw the result
+	circle(matBoard,maxLoc,1,Scalar(0),1);
+	circle(matBoard,minLoc,2,Scalar(255),2);
+	rectangle(matBoard,Rect(maxLoc.x - 10,maxLoc.y - 10,20,20),Scalar(0,0,255),-1);
+	return 0;
+}
+