C++ cmath cos() Function

The C++ cmath cos() function calculates the cosine of an angle provided in radians. It takes one required argument and returns a double value as an output, representing the cosine of that angle. This function is commonly used in trigonometry and physics for calculations involving cosine values.

Syntax

Following is the syntax for C++ cmath cos() function.

double cos(double x);
or
float cos(float x);
or
long double cos(long double x);

Parameters

• x - The angle in radians for which to calculate the cosine.

Return Value

The function returns the cosine of the given angle, as a floating-point value.

Time Complexity

The time complexity of this function is constant, i.e.,O(1).

Example 1

In the following example, we are going to calculate the cosine of a given angle in radians using cos() function.

#include <iostream>
#include <cmath>
int main() {
   double angle = 0.5;
   std::cout << "Cosine of 0.5 radians: " << std::cos(angle) << std::endl;
   return 0;
}

Output

If we run the above code it will generate the following output −

Cosine of 0.5 radians: 0.877583

Example 2

In this example, we will calculate the cosine of an angle after converting it from degrees to radians.

#include <iostream>
#include <cmath>
int main() {
   double angle_degrees = 60.0;
   double angle_radians = angle_degrees * (M_PI / 180.0); 
   std::cout << "Cosine of 60 degrees: " << std::cos(angle_radians) << std::endl;
   return 0;
}

Output

Following is the output of the above code

Cosine of 60 degrees: 0.5

Example 3

In this example, we are going to use std::cos in a loop to calculate and print the cosine values of angles from 0 to incrementing to /6 radians.

#include <iostream>
#include <cmath>
int main() {
   for (double angle = 0.0; angle <= M_PI; angle += M_PI / 6) {
      std::cout << "Cosine of " << angle << " radians: " << std::cos(angle) << std::endl;
   }
   return 0;
}

Output

Output of the above code is as follows

Cosine of 0 radians: 1
Cosine of 0.523599 radians: 0.866025
Cosine of 1.0472 radians: 0.5
Cosine of 1.5708 radians: 6.12323e-17
Cosine of 2.0944 radians: -0.5
Cosine of 2.61799 radians: -0.866025
Cosine of 3.14159 radians: -1