People often need a protractor in some cases. However, unless necessary, people usually do not carry the protractor on the body. Our team solved the problem well. We think about how to put the protractor in the phone so that it doesn't need to carry a protractor every time. This will make people more convenient. Our protractor is very convenient to use, only to click on the screen to confirm the start measure, then move the mobile phone, and the corresponding screen will show the current angle. After the user determines the current angle, he only needs to click on the phone screen again. APP will automatically fix the angle at this time. At the same time, our team has set up video tutorials in APP. Video will teach the user how to use it.