**3. VR systems**

VR can be enhanced by hearing technology. VR devices can be divided into three categories [4]:


One of the most used virtual reality systems that offer the most excellent immersion effect is the virtual helmet. Compared to other systems with an immersive effect, they are relatively cheap; the CAVE system can be given as an example of an expensive one. The HMD virtual helmet provides a truly immersive VR experience through two head-mounted displays, while desktop-based helmets require the helmet to be connected to a powerful gaming PC. Each eye has its own display. Unfortunately, however, this category of virtual reality device is not widely used because it is quite expensive. An all-in-one is a mid-range option; these devices do not require a computer connection. The low-level mobile VR product relies on VR Head Set. The main advantage is that it has a relatively low price and is convenient to work with. Today, many schools in Europe and worldwide are already improving the educational process through innovative modern methods based on new technologies. VR is one of the most advanced technologies, and it is normal for it to be used in primary and secondary schools today. It allows students to grasp complex concepts and definitions more easily. The main goal is to support student-centered teaching. There are documented results from using VR in secondary school mathematics learning, with increased

positive attitudes and interest in mathematics reported after using VR [5]. Another study concluded that students and teachers are open to a form of learning through VR and AR (Augmented Reality) [5]. In this way, students are helped to understand better geometric shapes that are difficult to represent. Virtual reality enables the user to use and interact with the virtual world similar to the real one [6]. VR finds application in many fields, such as flight simulation, motion simulation in physics and chemistry, etc. The output channels of virtual reality correspond to the human senses: vision and hearing. Vision is the most basic sense used. Stereoscopic vision is a primary human mechanism for depth perception. The techniques for stereoscopic vision are HMD, shutter, passive, and others. The main steps in implementing Virtual and Augmented Reality are.


Let us summarize that the 3D scene can be observed through a virtual reality viewer, such as an HMD or a normal desktop monitor. The user can move around the virtual environment using a mouse and keyboard. In this scene, 3D geometric figures are visible, allowing us to understand mathematical functions that are generally difficult to draw.
