How do you find the size of an angle without using a protractor?

Answer 1

If the angle is a lone, random angle, I believe you would need a protractor to determine the precise size of the angle (in "degrees"). However, you could, in this case, roughly guess as to whether the angle is acute, obtuse, or right (if the little rectangle is shown in the angle). Of course, if an angle is in a position where one can determine its measure using known postulates or theorems, finding the size of this angle becomes much easier. For example, if you know the measure of one angle and you must determine the measure of another angle, but these two angles are vertical angles, or are corresponding angles (by the corresponding angles postulate), you can indeed determine the measure of this angle without a protractor. Additionally, another example is that if you knew a pair of angles were either supplementary angles, complementary angles, or a linear pair, and you were given the measure of one of these angles, you could determine the measure of the other angle without a protractor. Therefore, it depends on the angle you're looking at.