Angles are usually measured using protractors.

度通常用进行测。

And he didn't use a protractor to make those perfect letters or any other kind of measurements.

他没有使用或任何其他测方式来些完美字母。

Protractors have markings on them, similar to rulers, but instead of inches or centimeters it measures in degrees.

上有何直尺类似刻度，但是其刻度不是英寸或者是厘米，而是以度来衡。

If you don't have a protractor to measure with, you can estimate how big it is as long as you remember what a 90 degree angle, 180 degree angle, and 360 degree angle look like.

如果你没有，你可以估计它有多大，只要你记得 90 度，180 度和 360 度是什么样子就行了。