Q:
A:
首先,根據三角形判定定理:兩邊之和大於第三邊,判斷是否是三角形。然後根據海倫定理,求得三角形的面積。接着,如果三邊相等是等邊三角形,兩邊相等爲等腰三角形,兩邊之和等於第三邊爲直角三角形。
#include<iostream>
#include <math.h>
using namespace std;
// Is it a triangle?
int main() {
//the edge of triangle.
float a, b, c,s,area;
cin>>a>>b>>c;
if (a + b > c && a + c > b && b + c > a) {
// Heron's formula
s = (a+b+c)/2.0;
area = sqrtf(s*(s-a)*(s-b)*(s-c));
cout<<"the area is: "<<area<<endl;
if(a==b && b ==c){
cout<<"the triangle is Equilateral triangle!"<<endl;
}else if(a==b || b==c || a==c){
if(pow(a,2)+pow(b,2)==pow(c,2)||pow(a,2)+pow(c,2)==pow(b,2)||pow(b,2)+pow(c,2)==pow(a,2)){
cout<<"the triangle is Isosceles right triangle!"<<endl;
}else{
cout<<"the triangle is Isosceles triangle!"<<endl;
}
}else if(pow(a,2)+pow(b,2)==pow(c,2)||pow(a,2)+pow(c,2)==pow(b,2)||pow(b,2)+pow(c,2)==pow(a,2)){
cout<<"the triangle is Right triangle!"<<endl;
}else {
cout<<"the triangle is ordinary triangle!"<<endl;
}
}else{
cout<<"not a triangle"<<endl;
}
return 0;
}