Graphing sin and cos functions

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Homework Help Overview

The discussion revolves around graphing the function x(t) = 10cos((pi*t)-(pi/4)), focusing on understanding its amplitude, frequency, and phase shift. Participants are examining the characteristics of the cosine function in relation to transformations applied to it.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the amplitude and phase shift of the function, with some questioning the interpretation of the radian frequency and its relationship to the period of the function. There are attempts to clarify how the transformations affect the graph, particularly regarding the intercepts and the overall shape.

Discussion Status

Some participants have provided insights into the relationship between angular frequency and the period of the function, while others are exploring the implications of the phase shift on the graph. There is an ongoing examination of the transformations without a clear consensus on the interpretation of the frequency.

Contextual Notes

There is a mention of homework constraints and the need to accurately represent the transformations in the graphing process. Participants are navigating through the implications of the function's parameters without resolving all uncertainties.

jayare81
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Homework Statement



plot x(t) = 10cos((pi*t)-(pi/4))

Homework Equations



pi/4 is the shift to the right

10 is the amplitude of the graph

pi is the radian frequency

The Attempt at a Solution



so i got the amplitude and shift to the right by pi/4 part but as for the radian frequency, my plot doesn't seem right. does pi mean that one cos wave occurs in a pi interval? thanks in advance
 
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Yes. pi is the angular frequency, w. How is it related to the time period, T?

ehild
 
jayare81 said:

Homework Statement



plot x(t) = 10cos((pi*t)-(pi/4))

Homework Equations



pi/4 is the shift to the right
I don't think so. You could write this function as x(t) = 10 cos(pi(t - 1/4)). The graph of x(t) = 10 cos(pi*t) has two transformations: a vertical expansion by a factor of 10 (that's your amplitude), and a compression toward the vertical axis by a factor of pi. This compression means that instead of having t intercepts at +/-pi/2, +/-3pi/2, +/-5pi/2, and so on, x(t) = 10 cos(pi*t) has t intercepts at +/-1/2, +/-3/2, +/-5/2, and so on.
The -1/4 term causes a shift to the right by 1/4 unit of the graph of x(t) = 10 cos(pi*t).
jayare81 said:
10 is the amplitude of the graph

pi is the radian frequency

The Attempt at a Solution



so i got the amplitude and shift to the right by pi/4 part but as for the radian frequency, my plot doesn't seem right. does pi mean that one cos wave occurs in a pi interval? thanks in advance
 
thanks for the help! T is 2pi/w so the period i got was 2. one cos wave occurs within 0-2
 
Yes, but do not forget that it is shifted, so its has the maximum value where (pi*t)-(pi/4)=0.

ehild
 

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