使用“边角边”的三角形面积(两个边的长度和夹角)

给定两个整数A ， B表示一个三角形的两个边的长度，以及一个整数K表示它们之间的弧度(弧度)，任务是根据给定的信息计算三角形的面积。
例子：

Input: a = 9, b = 12, K = 2 
Output: 49.1 
Explanation: 
Area of triangle = 1 / 2 * (9 * 12 * Sin 2) = 35.12
Input: A = 2, B = 4, K = 1 
Output: 3.37 
 

方法：
考虑下面的三角形ABC ，其边A ， B ， C以及边A和B之间的夹角K。

然后，可以使用Side-Angle-Side公式计算三角形的面积：

$Area (ABC) = \frac{1}{2} \ A * B * sin(K)$
 

下面是上述方法的实现：

C++

// C++ program to calculate
// the area of a triangle when
// the length of two adjacent
// sides and the angle between
// them is provided
#include 
using namespace std;
 
float Area_of_Triangle(int a, int b, int k)
{
    float area = (float)((1 / 2.0) *
                          a * b * (sin(k)));
 
    return area;
}
 
// Driver Code
int main()
{
    int a = 9;
    int b = 12;
    int k = 2;
 
    // Function Call
    float ans = Area_of_Triangle(a, b, k);
 
    // Print the final answer
    cout << ans << endl;
}
 
// This code is contributed by Ritik Bansal

Java

// Java program to calculate
// the area of a triangle when
// the length of two adjacent
// sides and the angle between
// them is provided
class GFG{
 
// Function to return the area of
// triangle using Side-Angle-Side
// formula
static float Area_of_Triangle(int a, int b,
                                     int k)
{
    float area = (float)((1 / 2.0) *
                      a * b * Math.sin(k));
 
    return area;
}
 
// Driver Code
public static void main(String[] args)
{
    int a = 9;
    int b = 12;
    int k = 2;
 
    // Function Call
    float ans = Area_of_Triangle(a, b, k);
 
    // Print the final answer
    System.out.printf("%.1f",ans);
}
}
 
// This code is contributed by sapnasingh4991

Python3

# Python3 program to calculate
# the area of a triangle when
# the length of two adjacent
# sides and the angle between
# them is provided
 
import math
 
# Function to return the area of
# triangle using Side-Angle-Side
# formula
def Area_of_Triangle(a, b, k):
 
    area =(1 / 2) * a * b * math.sin(k)
 
    return area
 
# Driver Code
a = 9
b = 12
k = 2
 
# Function Call
ans = Area_of_Triangle(a, b, k)
 
# Print the final answer
print(round(ans, 2))

C#

// C# program to calculate
// the area of a triangle when
// the length of two adjacent
// sides and the angle between
// them is provided
using System;
class GFG{
 
// Function to return the area of
// triangle using Side-Angle-Side
// formula
static float Area_of_Triangle(int a, int b,
                                     int k)
{
    float area = (float)((1 / 2.0) *
                  a * b * Math.Sin(k));
 
    return area;
}
 
// Driver Code
public static void Main(String[] args)
{
    int a = 9;
    int b = 12;
    int k = 2;
 
    // Function Call
    float ans = Area_of_Triangle(a, b, k);
 
    // Print the readonly answer
    Console.Write("{0:F1}", ans);
}
}
 
// This code is contributed by sapnasingh4991

Javascript

// javascript program to calculate
// the area of a triangle when
// the length of two adjacent
// sides and the angle between
// them is provided// Function to return the area of
// triangle using Side-Angle-Side
// formula
 
function Area_of_Triangle(a , b, k)
{
    var area = ((1 / 2.0) *
                      a * b * Math.sin(k));
 
    return area;
}
 
// Driver Code
var a = 9;
var b = 12;
var k = 2;
 
// Function Call
var ans = Area_of_Triangle(a, b, k);
 
// Prvar the final answer
document.write(ans.toFixed(1));
 
// This code is contributed by 29AjayKumar

输出：

49.1

时间复杂度： O(1)
辅助空间： O(1)