Reading the question carefully, "<span>He draws the diameter of the circle through center P using a straight edge. Next he opens his compass to a width equivalent to the radius of the circle." - that implies that Mateo is still in the process of drawing the circle by which the equilateral is inscribed to.
The next steps should be:
*He should draw the upper and lower arcs using the compass opened to a width equivalent to the radius of the sircle.
*Make a vertical diameter using centroid P as basis.
*Draw two right triangles facing the opposite directions using the top most point by which the vertical diameter of the circle touches the top most circumference of the circle.
Doing these steps, Mateo will be able to draw an equilateral triangle inscribed in a circle.
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Answer:
Step-by-step explanation:
The last three are irrational but I'm not sure about the first four.
For this case we have the following equation:

Let 
We have:

By definition, given an equation of the form 
The quadratic formula, to find the solution can be written as:

In this case we have:

Substituting in the quadratic formula we have:
See attached image
Answer:
Option B