Using proportions, it is found that the value of a is of 3.
<h3>What is a proportion?</h3>A proportion is a fraction of a total amount, and the measures are related using a rule of three.
In this problem, a 180º angle has a measure of radians. What is the measure of a 540º angle? The <em>rule of three</em> is given by:
180º - rad.
540º - x rad.
Applying cross multiplication:
180x = 540.
x = 540/180 = 3.
The value of a is of 3.
More can be learned about proportions at brainly.com/question/24372153