Determine all real numbers [tex]\( s \)[/tex] associated with the point [tex]\((x, y)\)[/tex] on the unit circle. Write the exact radian answer in [tex]\([0, 2\pi)\)[/tex] and indicate remaining answers using [tex]\( n \)[/tex] to represent any integer.

Given point: [tex]\(\left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex]



Answer :

To determine all the real numbers [tex]\( s \)[/tex] associated with the point [tex]\((x, y) = \left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex] on the unit circle, follow these steps:

### Step 1: Understand the Unit Circle

A point on the unit circle represents the cosine and sine values of an angle [tex]\(\theta\)[/tex]:
[tex]\[ (x, y) = (\cos(\theta), \sin(\theta)) \][/tex]
Given:
[tex]\[ x = -\frac{\sqrt{3}}{2} \quad \text{and} \quad y = \frac{1}{2} \][/tex]

### Step 2: Find the Principal Angle

To find the principal angle [tex]\(\theta\)[/tex] corresponding to the given point, we look at inverse trigonometric functions. Specifically, we can use the [tex]\(\text{arctan2}\)[/tex] function, which correctly handles the quadrant of the angle. The point [tex]\(\left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex] is in the second quadrant.

The principal angle [tex]\(\theta\)[/tex] in the range [tex]\([0, 2\pi)\)[/tex] is found to be:
[tex]\[ \theta \approx 2.6179938779914944 \text{ radians} \][/tex]
This means:
[tex]\[ \theta = \frac{5\pi}{6} \][/tex]

### Step 3: General Solution Using Periodicity

The unit circle is periodic with a period of [tex]\(2\pi\)[/tex]. Therefore, the general solution for the angle [tex]\(s\)[/tex] considering the periodic nature of trigonometric functions is given by:
[tex]\[ s = \theta + 2k\pi \quad \text{for any integer} \; k \][/tex]
Thus, the general solution is:
[tex]\[ s = \frac{5\pi}{6} + 2k\pi \][/tex]
where [tex]\( k \)[/tex] is any integer.

### Step 4: Consolidate the Answers

Hence, the exact answer within [tex]\([0, 2\pi)\)[/tex] is:
[tex]\[ s = \frac{5\pi}{6} \][/tex]
And the remaining solutions can be expressed using the periodicity:
[tex]\[ s = \frac{5\pi}{6} + 2k\pi \quad \text{where} \; k \; \text{is any integer} \][/tex]

By following these detailed steps, we have determined the principal angle and the general solution for all real numbers [tex]\(s\)[/tex] associated with the point [tex]\(\left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex] on the unit circle.

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