Find the reference angle of [tex]\frac{14 \pi}{11}[/tex].

A. [tex]-\frac{13 \pi}{11}[/tex]
B. [tex]\frac{13 \pi}{11}[/tex]
C. [tex]\frac{3 \pi}{11}[/tex]
D. [tex]-\frac{3 \pi}{11}[/tex]



Answer :

To find the reference angle of [tex]\(\frac{14\pi}{11}\)[/tex]:

Step 1: Convert the angle to the range [tex]\([0, 2\pi)\)[/tex]:
- The given angle is [tex]\(\frac{14\pi}{11}\)[/tex].
- This angle is already within the range [tex]\([0, 2\pi)\)[/tex] because [tex]\(2\pi = \frac{22\pi}{11}\)[/tex] and [tex]\(\frac{14\pi}{11}\)[/tex] is less than [tex]\(\frac{22\pi}{11}\)[/tex].

Step 2: Determine the reference angle based on the standard trigonometric definitions:
- If an angle θ is in Quadrant I, then its reference angle is θ.
- If an angle θ is in Quadrant II, then its reference angle is [tex]\(\pi - \theta\)[/tex].
- If an angle θ is in Quadrant III, then its reference angle is [tex]\(\theta - \pi\)[/tex].
- If an angle θ is in Quadrant IV, then its reference angle is [tex]\(2\pi - \theta\)[/tex].

Since [tex]\(\frac{14\pi}{11}\)[/tex] is greater than [tex]\(\pi\)[/tex] but less than [tex]\(2\pi\)[/tex], it ends up in Quadrant III:
- Here, we find the reference angle by using [tex]\(\theta - \pi\)[/tex].

Step 3: Calculate the reference angle:
- The original angle is [tex]\(\frac{14\pi}{11}\)[/tex].
- The reference angle in Quadrant III is given by:
[tex]\[ \frac{14\pi}{11} - \pi = \frac{14\pi}{11} - \frac{11\pi}{11} = \frac{3\pi}{11} \][/tex]

So, the reference angle of [tex]\(\frac{14\pi}{11}\)[/tex] is:
[tex]\[ \boxed{\frac{3\pi}{11}} \][/tex]

The numerical value of the reference angle [tex]\(\frac{3\pi}{11}\)[/tex] is approximately:
[tex]\[ 2.284794657156213 \][/tex]

Therefore, the correct answer is [tex]\(\frac{3\pi}{11}\)[/tex].

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