triangles & pythagorean

[aquaturtle]

I really need help with my c++
I need to write 4 functions:
1. findRightTriangles
2. area
3. congruent
4. similar

I think I might have done the findRightTriangle, not sure if its correct though. I am clueless how to do this, any insights or help is appreciated (like how to start on any of these functions; how to go about them).

#include "triangles.h" 
#include <iostream>
using std::cout;
#include <vector>
using std::vector;
#include <algorithm>
using std::sort;


unsigned long triangle::perimeter() {
	return s1+s2+s3;
}

unsigned long triangle::area() {
	unsigned long sides[3] = {s1, s2, s3};
	// TODO: write this function.
	// Note: why is it okay to return an integer here?  Recall that
	// all of our triangles have integer sides, and are right triangles...
	return 0;
}

void triangle::print() {
	cout << "[" << s1 << "," << s2 << "," << s3 << "]";
}

bool congruent(triangle t1, triangle t2) {
	// TODO: write this function.
	
	return false;
}

bool similar(triangle t1, triangle t2) {
	// TODO: write this function.

	return false;
}

vector<triangle> findRightTriangles(unsigned long l, unsigned long h) {
	// TODO: find all the right triangles with integer sides,
	// subject to the perimeter bigger than l and less than h
	vector<triangle> retval; // storage for return value.
	triangle t1;
	t1.s1=l;
	t1.s3=h;	
	for(unsigned long a=0; a< t1.s3; a++) {
		t1.s2=a;
		if(a >= t1.s1 && a <= t1.s3  && (((t1.s1*t1.s1)+(a*a)) == (t1.s3*t1.s3))) {
			retval.push_back(t1);
			break;
			}
		}

	return retval;
}

header file
triangles.h:

#pragma once

#include <vector>
using std::vector;

class triangle {
	public:
		// member functions:
		// constructor:
		triangle(unsigned long a=3, unsigned long b=4, unsigned long c=5):
			s1(a),s2(b),s3(c) {}
		unsigned long perimeter();
		unsigned long area();
		void print();  // prints to standard output
		// member variables:
		// integers for the 3 sides:
		unsigned long s1;
		unsigned long s2;
		unsigned long s3;
};

vector<triangle> findRightTriangles(unsigned long l, unsigned long h);
bool congruent(triangle t1, triangle t2);
bool similar(triangle t1, triangle t2);

[osgwsy]

1) First of all, I need to check with you, 'findRightTriangles' meaning checking if the triangle is a right-angle triangle? If is to check, you can use this formula to check: a^2+b^2 = c^2, where c is the longest side of the triangle.

2) For getting the area of the triangle, you can use Heron's formula. (http://en.wikipedia.org/wiki/Heron%27s_formula)

3) For checking of congruent, just check if the sides of the triangles are equal. This can be done by arranging the length of the triangle by increasing/decreasing order. After arranging, you can compare the lengths of the 2 triangles respectively.

4) For checking of similarity, you can use 'SSS' (side, side, side) test. This can be done, again, by first arranging the length of the triangle by increasing/decreasing order. After arranging, check the ratio respectively.

Hope these help :)

[aquaturtle]

Thanks for the reply!
findRightTriangles searches for right triangles satisfying certain conditions:
1. All the side lengths must be integers
2. The triangles must be right triangles
3. The perimeter must be bounded above and below any input paraameters that is, l <= perimeter <= h



I somewhat have the idea in my head of how to do each one, its just.. I don't know how to write a code for each of them

If it's possible, can someone show me an example of how to start making a code for one of the functions

[osgwsy]

Hi aquaturtle, I think understand what you want. Below is an example, hope it helps.

I have stored the sides of the triangle into a vector. So vector<int>trianglesides contains the 3 sides of the triangle. Not too sure if you are familiar with vector.

In addition, to use vector, you will need to include #include <vector> .

bool ifRightAngle(vector<int> trianglesides)
{
	sort(trianglesides.begin(), trianglesides.end()); //have to include "#include <algorithm>"
	if ((pow(double(trianglesides.at(0)),2)+pow(double(trianglesides.at(1)),2)) == pow(double(trianglesides.at(2)),2))
		return true;	//Is a right angle triangle
	else 
		return false;	//Is not a right angle triangle
}

bool perimeterCheck(vector<int> trianglesides)
{
	int nSum = trianglesides.at(0)+trianglesides.at(1)+trianglesides.at(2);
	int nSum_lower = 10;
	int nSum_upper = 100;
	if (nSum_lower < nSum && nSum < nSum_upper)
		return true; //Meet the requirement
	else 
		return false;//Did not meet the requirement
}