class triangle
{
public:
CPoint p[3];
double Area()//面积
{
double s=0;
int i;
for(i=0;i<3;i++)s+=(p[i].x*p[(i+1)%3].y-p[i].y*p[(i+1)%3].x);
return fabs(s/2);
}
double C()//周长
{
double s=0;
int i;
for(i=0;i<3;i++)
s+=sqt((p[i].x-p[(i+1)%3].x)*(p[i].x-p[(i+1)%3].x)+
(p[i].y-p[(i+1)%3].y)*(p[i].y-p[(i+1)%3].y)); return s;
}
... ...
};
{
public:
CPoint p[3];
double Area()//面积
{
double s=0;
int i;
for(i=0;i<3;i++)s+=(p[i].x*p[(i+1)%3].y-p[i].y*p[(i+1)%3].x);
return fabs(s/2);
}
double C()//周长
{
double s=0;
int i;
for(i=0;i<3;i++)
s+=sqt((p[i].x-p[(i+1)%3].x)*(p[i].x-p[(i+1)%3].x)+
(p[i].y-p[(i+1)%3].y)*(p[i].y-p[(i+1)%3].y)); return s;
}
... ...
};
private int a,b,c;
public Triangle(int a,int b,int c){
if(a>0&&b>0&&c>0){
if(a+b>c&&a+c>b&&c+b>a){
this.a=a;
this.b=b;
this.c=c;
}
}
else{System.out.println("not a valid Triangle");}
}
public int getL(){
return a+b+c;
}
}
其它根据几何定理的只需组合一下a,b,c
import java.util.*;public class triangleclass{
public static void main(String args[]) throws Exception {
triangle object1=new triangle();
object1.setAttribute(3,4,5);
System.out.println("三角形的周长是:"+object1.grith());
System.out.println("三角形的面积是:"+object1.area());
System.out.println("内切圆面积是:"+object1.incirclearea());
System.out.println("外接圆面积是:"+object1.circumcirclearea());
}
}
2、triangle.javaimport java.io.*;
import java.util.*;
import java.math.*;public class triangle{
private int bc1,bc2,bc3;
public int grith(){
System.out.print("三角形的边长是:"+bc1+" "+bc2+" "+bc3);
return bc1+bc2+bc3;
}
public double area(){
double area;
int p=(bc1+bc2+bc3)/2;
area=Math.sqrt(p*(p-bc1)*(p-bc2)*(p-bc3));
return area;
}public double incirclearea(){
double r,insidearea;
double area;
int p=(bc1+bc2+bc3)/2;
area=Math.sqrt(p*(p-bc1)*(p-bc2)*(p-bc3));
r=2*area/(bc1+bc2+bc3);
insidearea=3.14*r*r;
return insidearea;
}public double circumcirclearea(){
double R,outsidearea;
double area;
int p=(bc1+bc2+bc3)/2;
area=Math.sqrt(p*(p-bc1)*(p-bc2)*(p-bc3));
R=bc1*bc2*bc3/(4*area);
outsidearea=3.14*R*R;
return outsidearea;
}public void setAttribute(int x,int y,int z){
bc1=x;
bc2=y;
bc3=z;
}
}