Graph of Cardioid Solution with Cosine Calculation

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SUMMARY

The discussion centers on the calculation of cosine values in trigonometry, specifically addressing the confusion around the cosine of π/3. The correct value is established as cos(π/3) = 1/2, contradicting the initial claim that it equals √3/2. The participant acknowledges a mix-up between π/6 and π/3, leading to the misunderstanding of the equation 1 - cos(π/3) = 1/2. This clarification resolves the discrepancy with the textbook answer.

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bobsmith76
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Homework Statement



Screenshot2012-02-15at74132PM.png

The Attempt at a Solution



I don't see how they get

1 - cos (pi/3) = 1/2

cos (pi/3) = √3/2

1 - √3/2 = .14, not .5 like the book says

for the other figures I agree with the book.
 
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bobsmith76 said:

Homework Statement



Screenshot2012-02-15at74132PM.png



The Attempt at a Solution



I don't see how they get

1 - cos (pi/3) = 1/2
What's not to get? cos([itex]\pi[/itex]/3) = 1/2.

You need to brush up on your trig.
bobsmith76 said:
cos (pi/3) = √3/2
No, this is not true. sin([itex]\pi[/itex]/3) = √3/2.
bobsmith76 said:
1 - √3/2 = .14, not .5 like the book says

for the other figures I agree with the book.
 
never mind, I was mixing pi/6 up with pi/3
 

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