query_asst_2

course Mth 164

̅wxKƶLݐassignment #002

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002.

Precalculus II

01-30-2007

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13:51:33

query ch. 5.2 # 102 f(x) = cos(x), f(a) =1/4, find f(-a), f(a) + f(a+2`pi) + f(a - 2 `pi)

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RESPONSE -->

f(-a)= - cos 1/4 = - 1/4

f(a) + f(a+2pi)+f(a-2pi) = 1/4 + 1/4 + 1/4 = 3/4

confidence assessment: 2

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13:53:15

What is the value of f(a) + f(a+2`pi) + f(a - 2 `pi) and how did you use the even-odd and/or periodic properties of the function to obtain your result?

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RESPONSE -->

The value of f(a) + f(a+2pi) + f(a-2pi) is 3*f(a) essentially because it is known that f(a+2pi) = f(a) and that f(a-2pi) = f(a) also, so the result is f(a)+f(a)+f(a).

confidence assessment: 3

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13:53:22

query (no summary needed)

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RESPONSE -->

confidence assessment:

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13:55:01

How does the circular model demonstrate the periodic nature of the trigonometric functions? Be specific.

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RESPONSE -->

The circular model demonstrates the periodic nature of the trigonometric functions because the resulting graph follows a point moving around the circle at a constant speed, this produces maximum and minimum values (peaks) that occur at a frequency dependent on the linear speed of the point circling the circle, the sine function is the y value on the circular graph for example, when the point revolves around, the sine function can be graphed by the changing y values over a period of time.

confidence assessment: 2

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13:56:40

How does the circular model demonstrate the even or odd nature of the sine and cosine functions? Be specific.

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RESPONSE -->

The even or odd nature of the sine and cosine functions are demonstrated by the circular model becuase if theta is reflected over the x axis standard position and becomes - theta then there are points (x,y) for theta and points (x, -y) for negative theta, therefore sin theta = y and cos theta = x becomes sin (-theta) = -y and cos (-theta) = x.

confidence assessment: 3

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13:56:58

Can you very quickly sketch on a reference circle the angles which are multiples of `pi/6 and immediately list the sine and cosine of each? Can you do the same for multiples of `pi/4? (It's OK to answer honestly but be prepared to have to do this on a test, and remember that this task is central to understanding the trigonometric functions; if you've reached this point without that skill you have already wasted a lot of time by not knowing something you need to know to do what you're trying to do).

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RESPONSE -->

Yes, I have memorized the lovely unit circle.

confidence assessment: 3

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13:57:03

Comm on any surprises or insights you experienced as a result of this assignment.

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RESPONSE -->

confidence assessment:

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Very good answers. Let me know if you have questions.