If you want to learn geometry, protractors are going to be essential. They’ll help you get all the angles right. And if you have some problem with your existing protractor, here are some printable ones for you. Just take a printout, take a cut-out and paste on a cardboard cut in the same shape. And you can have as many protractors of as many sizes you want.
Printable Protractors for You
The following selection is basically everything one can ask for from a protractor, well-marked angles, and semi-circular or full-circular designs. One of these even has a dedicated ruler for you to use in case you need it.
Protractors are nice to use when you are learning, but it is also useful to have an idea about the angles and their measurements, so you can use your good eyesight to pinpoint them. And to achieve that, have the practice of using your protractors every time you are drawing an angle.