Question

我们必须让用户输入6个点，然后计算它们之间形成的三角形的面积。

这是我的代码：

//Purpose of the program is to have the user input 6 points, have a triangle made from those points and then calculate the area of said triangle

int main()
{
   //declaring variables. point1x is the x value for point 1 etc etc
    float point1x;
    float point1y;
    float point2x;
    float point2y;
    float point3x;
    float point3y;
    float side1;
    float side2;
    float side3;
    float svariable;
    float triangleArea;
//getting user to enter in the points
    printf ("Please enter point 1x: ");
    scanf ("%point1x", &point1x);


    printf ("Please enter point 1y: ");
    scanf ("%point1y", &point1y);


    printf ("Please enter point 2x: ");
    scanf ("%point2x", &point2x);


    printf ("Please enter point 2y: ");
    scanf ("%point2y", &point2y);


    printf ("Please enter point 3x: ");
    scanf ("%point3x", &point3x);


    printf ("Please enter point 3y: ");
    scanf ("%point3y", &point3y);

//calculating the lengths of the triangle

    side1=sqrt(((point1x-point2x)*(point1x-point2x))+((point1y-point2y)*(point1y-point2y)));

    side2=sqrt(((point1x-point3x)*(point1x-point3x))+((point1y-point3y)*(point1y-point3y)));

    side3=sqrt(((point2x-point3x)*(point2x-point3x))+((point2y-point3y)*(point2y-point3y)));

//svalue is needed for Heron's formula

    svariable=(((side1)*(side2)*(side3))/2);

//implementing herons formula

    triangleArea=(sqrt(svariable*(((svariable-side1)*(svariable-side2)*(svariable-side3)))));


    printf("the triangle area is: %f", triangleArea);

}

我不知道出了什么问题以及为什么它不起作用。我也无法在数学中看到问题。我正在使用Heron的配方。

Answer 1

在数学方面，你误解了苍鹭的公式：

svariable=(((side1)*(side2)*(side3))/2);

应该是

svariable= (side1 + side2 + side3) / 2.0;

Answer 2

可能还有其他问题，但最明显的一个问题是您错误地使用了scanf。这是正确的用法，这里有一些documentation。

  printf ("Please enter point 1x: ");
  scanf ("%f", &point1x);

Answer 3

首先，您需要加入stdio.h和math.h

#include <stdio.h>
#include <math.h>

在scanf调用中，您将要将字符串更改为期望浮点数的格式字符串。

示例：scanf("%f", &point1x);

为您的所有scanf电话执行此操作。

Answer 4

我会使用交叉产品功能计算区域：

V1 X V2 = area contained by those two vectors

因此，为了使三角形的面积在3个点之间，使用任意两个向量（边）就足够了如下：

v1 = p1p2
v2 = p1p3

v1_x = (x2 - x1)
v1_y = (y2 - y1)
v2_x = (x3 - x1)
v2_y = (y3 - y1)

CROSS = v1_X * v2_y - v1_y * v2_x

和

area = CROSS /2

无法显示三角形区域

4 个答案: