Math Problem Statement

wht is the exact value of cos 11 pie over 6

Solution

To find the exact value of cos(11π6)\cos\left(\frac{11\pi}{6}\right), follow these steps:

  1. Convert the angle 11π6\frac{11\pi}{6} into degrees: 11π6×180π=330\frac{11\pi}{6} \times \frac{180^\circ}{\pi} = 330^\circ

  2. Determine the reference angle: The reference angle for 330330^\circ is 360330=30360^\circ - 330^\circ = 30^\circ.

  3. Evaluate the cosine of the reference angle: cos(30)=32\cos(30^\circ) = \frac{\sqrt{3}}{2}.

  4. Determine the sign of the cosine in the fourth quadrant: Since 330330^\circ is in the fourth quadrant, where the cosine function is positive, cos(330)=32\cos(330^\circ) = \frac{\sqrt{3}}{2}.

So, the exact value of cos(11π6)\cos\left(\frac{11\pi}{6}\right) is 32\frac{\sqrt{3}}{2}.

Would you like any more details, or do you have any questions?

Here are some related questions:

  1. What is the exact value of sin(11π6)\sin\left(\frac{11\pi}{6}\right)?
  2. How do you find the sine and cosine of an angle greater than 2π2\pi?
  3. What is the reference angle for 13π6\frac{13\pi}{6}?
  4. How does the unit circle help in finding trigonometric values?
  5. What are the signs of trigonometric functions in each quadrant?

Tip: Always consider the quadrant in which an angle lies when determining the sign of its trigonometric functions.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Unit Circle
Angle Conversion

Formulas

Cosine function

Theorems

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Suitable Grade Level

High School