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reference distress
#171072
11/19/07 06:01 AM

Joined: Jun 2007
Posts: 20
OP
Member

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



Re: reference distress
[Re: Angel_Electric]
#171077
11/19/07 08:10 AM

Joined: Feb 2002
Posts: 183
Member

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.



Re: reference distress
[Re: n1ist]
#171086
11/19/07 01:11 PM

Joined: Dec 2003
Posts: 751
Member

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




