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#171072  11/19/07 07:01 AM
reference distress

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Joined: Jun 2007
Posts: 20
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First I attempted to post this question in the technical forum but was rejected so I hope its ok that I place this here for now. I'm currently attempting to delve into a book called Alternating Current Fundamentals / Sixth Edition(Delmar Thomson Learning), I'm hoping someone might have some form of familiarity with this text.Chapter 1 Achievement review Question #5(If the rotating line of figure 18 has a length of one unit,determine its projection or shadow on the x & Y Axes at 30 degrees, 45 degrees, 120 degrees,and 240 degrees.)Refer to Fig. 18 and appendices 4&5. I simply don't get what is expected of me, in the whole question. Any help would be appreciated



#171077  11/19/07 09:10 AM
Re: reference distress
[Re: Angel_Electric]


Just guessing from your description:
You have 4 cases. In each case, there is a line of 1 unit long, one end at the origin (0,0) where the angle between the line and the xaxis is 30, 45, 120, and 240 degrees (one per case).
They want to know if you draw lines from the other end to the X and Y axes, where do they cross them?
The original line, the axis, and the projected line form a right triangle with the 1unit line being the hypotenuse. The definitions of sine and cosine (sine = opposite/hypotenuse, cosine = adjacent/hypotenuse) will let you calculate the answer.
One thing to be careful of, most calculators expect the angles to be in radians, not degrees.



#171086  11/19/07 02:11 PM
Re: reference distress
[Re: n1ist]


I do believe the answer to the question is the shadow on the xaxis corresponds to a sine wave, and the shadow on the yaxis corresponds to a cosine wave.
Earl




