// Create a new vector with components (1, 2, 3) btVector3 vec(1, 2, 3); // Calculate and print the length of the vector float length = vec.length(); std::cout << "The length of vec is: " << length << std::endl; // Normalize the vector to a unit vector vec.normalize(); std::cout << "The normalized vec is: (" << vec.x() << ", " << vec.y() << ", " << vec.z() << ")" << std::endl;In the first example, we create a new btVector3 object with the components (1, 2, 3). We then call the length() method on the vector, which returns the magnitude or length of the vector as a float. The result is printed to the console. In the second example, we normalize the vector to a unit vector by calling the normalize() method on the vector object. This modifies the original vector to have a length of 1 while preserving its direction. We then print the components of the normalized vector to the console. The btVector3 class and its length() method are part of the Bullet Physics library, a popular open-source physics simulation engine for video games and other interactive applications.