Solution 4.3:1a

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m (Lösning 4.3:1a moved to Solution 4.3:1a: Robot: moved page)
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{{NAVCONTENT_START}}
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If we draw the angle
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<center> [[Image:4_3_1_a.gif]] </center>
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<math>{\pi }/{5}\;</math>
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on a unit circle, then it will have an
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<math>x</math>
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-coordinate that is equal to
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<math>{\cos \pi }/{5}\;</math>
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.
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<center> [[Image:4_3_1a.gif]] </center>
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FIGURE 1 FIGURE 2
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{{NAVCONTENT_STOP}}
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the line
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<math>x={\cos \pi }/{5}\;</math
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the line
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<math>x={\cos \pi }/{5}\;</math>
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In the figures, we see also that the only other angle between
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<math>0</math>
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and
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<math>2\pi </math>
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which has the same cosine value, i.e. same
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<math>x</math>
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-coordinate, is the angle
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<math>v=-\frac{\pi }{5}+2\pi =\frac{9\pi }{5}</math>
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on the opposite side of the
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<math>x</math>
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-axis.

Revision as of 11:44, 12 September 2008

If we draw the angle \displaystyle {\pi }/{5}\; on a unit circle, then it will have an \displaystyle x -coordinate that is equal to \displaystyle {\cos \pi }/{5}\; .

FIGURE 1 FIGURE 2 the line \displaystyle x={\cos \pi }/{5}\;x={\cos \pi }/{5}\;


In the figures, we see also that the only other angle between \displaystyle 0 and \displaystyle 2\pi which has the same cosine value, i.e. same \displaystyle x -coordinate, is the angle \displaystyle v=-\frac{\pi }{5}+2\pi =\frac{9\pi }{5} on the opposite side of the \displaystyle x -axis.

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