//mypoint.h class myPoint { public: myPoint(); myPoint(double x, double y); double getX(); double getY(); private: double mX,mY; };

好的，根据您给出的点类定义，我可以为您提供构造线三角形类的代码，如下所示：

#include <cmath>
#include "mypoint.h"

class myLine {
public:
    myLine(myPoint p1, myPoint p2): mP1(p1), mP2(p2) {}

    double getLength() {
        double x1 = mP1.getX(), y1 = mP1.getY();
        double x2 = mP2.getX(), y2 = mP2.getY();
        return std::sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
    }

private:
    myPoint mP1, mP2;
};

class myTriangle {
public:
    myTriangle(myPoint p1, myPoint p2, myPoint p3): mP1(p1), mP2(p2), mP3(p3) {}

    void print() {
        std::cout << "三角形的三个顶点为：" << std::endl;
        std::cout << "A(" << mP1.getX() << ", " << mP1.getY() << ")" << std::endl;
        std::cout << "B(" << mP2.getX() << ", " << mP2.getY() << ")" << std::endl;
        std::cout << "C(" << mP3.getX() << ", " << mP3.getY() << ")" << std::endl;
        std::cout << "三边长分别为：" << std::endl;
        std::cout << "AB = " << mL1.getLength() << std::endl;
        std::cout << "BC = " << mL2.getLength() << std::endl;
        std::cout << "CA = " << mL3.getLength() << std::endl;
        std::cout << "三角形的周长为：" << getPerimeter() << std::endl;
        std::cout << "三角形的面积为：" << getArea() << std::endl;
    }

    double getPerimeter() {
        return mL1.getLength() + mL2.getLength() + mL3.getLength();
    }

    double getArea() {
        double a = mL1.getLength(), b = mL2.getLength(), c = mL3.getLength();
        double p = (a + b + c) / 2;
        return std::sqrt(p * (p - a) * (p - b) * (p - c));
    }

private:
    myPoint mP1, mP2, mP3;
    myLine mL1{mP1, mP2}, mL2{mP2, mP3}, mL3{mP3, mP1};
};

您可以在主函数中使用该类进行测试，如下所示：

#include <iostream>
#include "mytriangle.h"

int main() {
    myPoint p1(0, 0), p2(0, 1), p3(1, 0);
    myTriangle tri(p1, p2, p3);
    tri.print();
    return 0;
}

样例输出：

三角形的三个顶点为：
A(0, 0)
B(0, 1)
C(1, 0)
三边长分别为：
AB = 1
BC = 1.41421
CA = 1.41421
三角形的周长为：3.41421
三角形的面积为：0.5