Explementary Angles

Explementary angles are two angles whose measures add up to 360 degrees, forming a complete circle.
example of explementary angles

In other words, two explementary angles create a full rotation around a circle.

A Practical Example

Let's consider two angles. One angle, alpha, measures 60°, and another angle, beta, measures 300°.

$$ \alpha = 60° $$

$$ \beta = 300° $$

If we add these two angles together, we get a total of 360 degrees.

$$ \alpha + \beta = 60° + 300° = 360° $$

This means that these two angles are explementary.

example of explementary angles

Another example could be a right angle of 90 degrees and an angle of 270 degrees. In this case, the sum of the measures is 360 degrees, making these two angles explementary. $$ 90° + 270° = 360° $$ Similarly, any other combination of angles that adds up to a full circle are explementary. $$ \alpha + \beta = 360° $$

Notes

Here are some additional notes on explementary angles:

  • The definition of explementary angles applies only to pairs of angles. Therefore, a single angle cannot be "explementary."
  • Explementary angles belong to the category of angles associated by their measures, which includes complementary angles (sum is 90°), supplementary angles (sum is 180°), and explementary angles (sum is 360°).
  • Given any angle alpha, you can find the other angle beta that forms an explementary pair by subtracting alpha from 360°. $$ \beta = 360° - \alpha $$ For example, if angle alpha is 120°, the other angle in the explementary pair would be 240°. $$ \beta = 360° - 120° = 240° $$
  • If a concave angle and a convex angle share the same sides and vertex, then they are an explementary pair.

And so on.

 

 
 

Please feel free to point out any errors or typos, or share suggestions to improve these notes. English isn't my first language, so if you notice any mistakes, let me know, and I'll be sure to fix them.

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Angles (Geometry)