Evaluate cos(arccos((32pi)/3)) (I think I know how, just need someone to confirm)

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In summary, to evaluate cos(arccos((32pi)/3)), you need to find the angle whose cosine is (32pi)/3 and then take the cosine of that angle. However, since the argument is outside the domain of arccos, the problem may have no solution.
  • #1
Ianfinity
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Evaluate cos(arccos((32pi)/3))

From my understanding, I need to subtract (32pi)/3 by pi until the answer falls within the domain of [-1, 1]. Is this the correct way to solve this problem?
 
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  • #2
Are you sure you don't mean [itex]\arccos(\cos(\frac{32\pi}3))[/itex] instead of [itex]\cos(\arccos(\frac{32\pi}3))[/itex] ?
 
  • #3
Yes, I am sure. It IS possible, however, that the problem has no solution, if that's what you're getting at.
 
  • #4
What is the domain of arccos? Also, this shouldn't be in the "Calculus and Beyond" section of the forum...
 
  • #5
Ianfinity said:
Evaluate cos(arccos((32pi)/3))

From my understanding, I need to subtract (32pi)/3 by pi until the answer falls within the domain of [-1, 1]. Is this the correct way to solve this problem?
No. That's not the way to solve this.

See Ansatz7's post above.
 

1. How do you evaluate cos(arccos((32pi)/3))?

To evaluate this expression, we need to understand what each component represents. Arccos is the inverse function of cosine, so it undoes the effect of cosine. In other words, it gives us the angle whose cosine is whatever value is inside the parentheses. In this case, the value inside the parentheses is (32pi)/3. This means that cos(arccos((32pi)/3)) is asking for the cosine of the angle whose cosine is (32pi)/3. Since the cosine of any angle is always between -1 and 1, we can conclude that cos(arccos((32pi)/3)) = (32pi)/3.

2. Why is cos(arccos((32pi)/3)) equal to (32pi)/3?

This is because the expression cos(arccos((32pi)/3)) is asking for the cosine of the angle whose cosine is (32pi)/3. Since cosine is the ratio of the adjacent side to the hypotenuse in a right triangle, it can never be greater than 1. Therefore, the angle whose cosine is (32pi)/3 must have a measure of (32pi)/3.

3. Can this expression be simplified further?

No, this expression cannot be simplified further. The value (32pi)/3 is its simplest form and cannot be reduced any further.

4. What is the significance of using arccos in this expression?

The use of arccos in this expression allows us to find the value of cos(arccos((32pi)/3)), which is the cosine of the angle whose cosine is (32pi)/3. This is a useful tool in solving trigonometric equations and finding unknown angles in right triangles.

5. How can I use this expression in real-life situations?

This expression can be used in various real-life situations, such as calculating angles in architecture and engineering, determining the position of objects in space, and solving problems in physics and astronomy. It is also a fundamental concept in understanding circular motion and waves.

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