Math CentralQuandaries & Queries


Question from Malik:

Do all angles have to be equal to a number? By all angles I mean adjacent, vertical, supplementary, complementary.

Hi Malik,

An angle is a geometric concept. Wikipedia's definition is "In plane geometry, an angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle." We often are interested in the size of an angle, usually called the measure of the angle, and commonly use the units of degrees. Often we confuse the concepts by saying "the angle is 30 degrees" when we should say "the measure of the angle is 30 degrees". The concepts of adjacent, vertical, supplementary, and complementary can be defined in terms of the angle without reference to its measure.

I hope this helps,

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