Select the correct answer.

What is the corresponding point on the unit circle for the given radian measure [tex]\theta=\frac{5 \pi}{2}[/tex]?

A. [tex]\left(-\frac{1}{2}, \frac{\sqrt{3}}{2}\right)[/tex]
B. [tex]\left(\frac{\sqrt{3}}{2}, \frac{1}{2}\right)[/tex]
C. [tex]\left(\frac{1}{2}, -\frac{\sqrt{3}}{2}\right)[/tex]
D. [tex]\left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)[/tex]



Answer :

To determine the corresponding point on the unit circle for the angle [tex]\(\theta = \frac{5\pi}{2}\)[/tex], follow these steps:

1. Normalize the Angle:
The given angle is [tex]\(\theta = \frac{5\pi}{2}\)[/tex]. This angle is beyond one full revolution ([tex]\(2\pi\)[/tex]). To find the equivalent angle within a single revolution, we need to reduce the angle:
[tex]\[ \theta \mod 2\pi = \frac{5\pi}{2} \mod 2\pi \][/tex]

Simplifying,
[tex]\[ \frac{5\pi}{2} = 2\pi + \frac{\pi}{2} \][/tex]

So,
[tex]\[ \frac{5\pi}{2} \mod 2\pi = \frac{\pi}{2} \][/tex]

Therefore, [tex]\(\theta = \frac{\pi}{2}\)[/tex] is the equivalent angle within one revolution.

2. Determine the Point on the Unit Circle:
The angle [tex]\(\frac{\pi}{2}\)[/tex] corresponds to [tex]\(\frac{\pi}{2}\)[/tex] radians, which is the upward positive y-direction on the unit circle (90 degrees).

The cosine of [tex]\(\frac{\pi}{2}\)[/tex] is:
[tex]\[ \cos\left(\frac{\pi}{2}\right) = 0 \][/tex]

The sine of [tex]\(\frac{\pi}{2}\)[/tex] is:
[tex]\[ \sin\left(\frac{\pi}{2}\right) = 1 \][/tex]

Therefore, the coordinates corresponding to [tex]\(\theta = \frac{\pi}{2}\)[/tex] on the unit circle are [tex]\((0, 1)\)[/tex].

3. Verify the Point:
Checking against the answer choices:

- A. [tex]\(\left(-\frac{1}{2}, \frac{\sqrt{3}}{2}\right)\)[/tex]
- B. [tex]\(\left(\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex]
- C. [tex]\(\left(\frac{1}{2}, -\frac{\sqrt{3}}{2}\right)\)[/tex]
- D. [tex]\(\left(-\frac{\sqrt{3}}{2}, \frac{1}{2}\right)\)[/tex]

None of these points match the calculated point [tex]\((0, 1)\)[/tex]. Hence, none of the provided options (A, B, C, or D) are correct.

4. Conclusion:
The corresponding point on the unit circle for [tex]\(\theta = \frac{5\pi}{2}\)[/tex] is [tex]\((0, 1)\)[/tex], which corresponds to none of the answer choices. Thus, the correct point is:
[tex]\[ (0, 1) \][/tex]

Hence, the provided options do not match the result obtained from normalizing the angle and calculating the trigonometric values.