#include <iostream>
#include <iomanip>
#define _USE_MATH_DEFINES // for M_PI
#include <math.h>
using namespace std;
int main()
{
int a_base = 3, b_left_side = 4, c_right_side = 5;
float perimeter = a_base + b_left_side + c_right_side;
cout << "Perimeter = " << fixed << setprecision(2) << perimeter << endl;
float semi_perimeter = (a_base + b_left_side + c_right_side) / 2;
double area_triangle1 = sqrt(semi_perimeter * (semi_perimeter - a_base) *
(semi_perimeter - b_left_side) *
(semi_perimeter - c_right_side));
cout << "Area triangle1 = " << fixed << setprecision(2) << area_triangle1 << endl;
int b_base = 4, a_right_side = 6, angle_ab = 55;
double area_triangle2 = (a_right_side * b_base * sin((M_PI / 180) * angle_ab)) / 2;
cout << "Area triangle2 = " << fixed << setprecision(2) << area_triangle2 << endl;
int height = 5;
b_base = 8;
double area_triangle3 = (b_base * height) / 2;
cout << "Area triangle3 = " << fixed << setprecision(2) << area_triangle3 << endl;
return 0;
}
/*
run:
Perimeter = 12.00
Area triangle1 = 6.00
Area triangle2 = 9.83
Area triangle3 = 20.00
*/
