Graphing sin and cos functions

In summary, the homework statement says that the graph of x(t) = 10 cos(pi*t) will have 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. The -1/4 term causes a shift to the right by 1/4 unit of the graph of x(t) = 10 cos(pi*t). The amplitude and shift to the right are both described by pi/4. The period is 2pi/w, which means that one cos wave will have a maximum value of (pi*t)-(pi/4)=0.
  • #1
jayare81
2
0

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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  • #2
Yes. pi is the angular frequency, w. How is it related to the time period, T?

ehild
 
  • #3
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
 
  • #4
thanks for the help! T is 2pi/w so the period i got was 2. one cos wave occurs within 0-2
 
  • #5
Yes, but do not forget that it is shifted, so its has the maximum value where (pi*t)-(pi/4)=0.

ehild
 

FAQ: Graphing sin and cos functions

What is a sine function?

A sine function is a mathematical function that describes a wave-like pattern. It is defined as the ratio of the opposite side to the hypotenuse in a right triangle.

What is a cosine function?

A cosine function is a mathematical function that describes a wave-like pattern. It is defined as the ratio of the adjacent side to the hypotenuse in a right triangle.

What is the period of a sine function?

The period of a sine function is the distance between two consecutive peaks or troughs. It is equal to 2π or the length of one complete cycle.

What is the amplitude of a cosine function?

The amplitude of a cosine function is the distance from the midline to the peak or trough. It is equal to the absolute value of the coefficient in front of the cosine function.

How do you graph a sine or cosine function?

To graph a sine or cosine function, you can plot points using the x and y values from the function or use a graphing calculator. The x-values represent the angle in radians and the y-values represent the output of the function. You can also use the amplitude, period, and phase shift to help with graphing.

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