Math Problem Statement
Question 7(Multiple Choice Worth 3 points) (05.05 MC)
Given x equals pi over 6 comma what is the exact value of cos(2π − x)?
one half negative one half radical 3 over 2 negative radical 3 over 2
Solution
We are given that , and we are asked to find the exact value of .
Step 1: Substitute the given value of into the expression.
We know that , so we substitute it into :
Step 2: Simplify the angle.
We simplify . First, express with a common denominator: Now subtract from :
Step 3: Find the cosine of the angle .
The angle lies in the fourth quadrant, where cosine is positive. To find the cosine, we calculate the reference angle. The reference angle is: We know that .
Since is in the fourth quadrant, where cosine is positive, we have:
Final Answer:
The exact value of is .
Thus, the correct answer is , which corresponds to: Radical 3 over 2.
Would you like more details or have any further questions on this? Here are some related questions to explore:
- How does the cosine function behave in different quadrants?
- What is the reference angle for angles in the second and third quadrants?
- Can you derive the cosine and sine of common angles like , , etc.?
- How do you apply trigonometric identities to simplify expressions?
- How do you solve for exact values of trigonometric functions at non-standard angles?
Tip: Remember that the cosine function is positive in the first and fourth quadrants and negative in the second and third quadrants.
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Math Problem Analysis
Mathematical Concepts
Trigonometry
Cosine Function
Quadrants of the Unit Circle
Formulas
cos(2π − x) = cos(2π − x)
Theorems
Cosine function behavior in different quadrants
Reference angle in trigonometry
Suitable Grade Level
Grades 9-12