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Solution 4.2:3d

From Förberedande kurs i matematik 1

Revision as of 12:06, 28 September 2008 by Ian (Talk | contribs)
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In order to get an angle between 0 and 2, we subtract 2 from 72 , which also leaves the cosine value unchanged


cos27=cos272=cos23 


When we draw a line which makes an angle 32 with the positive x -axis, we get the negative y -axis and we see that this line cuts the unit circle at the point 01 . The x -coordinate of the intersection point is thus 0 and hence cos72=cos32=0