Very easy question

  • Thread starter Karma
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  • #1
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sin-(cos(17pi/5))

cos=(x+n2pi)=cos(x)

I know that this becomes 7pi/5.. But what is substituted for the integer value? and why? (how does it become 7pi/5)
 

Answers and Replies

  • #2
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because cosinus is periodic with period 2pi. So if you add 2pi in the argument you get the same result.
 
  • #3
HallsofIvy
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sin-(cos(17pi/5))

cos=(x+n2pi)=cos(x)
It's not at all clear what you mean by "sin-(cos(17pi/5)". do you mean 'sine or cosine of that'? And, of course the "=" in "cos=" is a typo.

17/5= 3 and 2/5= 2+ (1+ 2/5). The "n" in "n2pi" is 1 and the "x" is (1+ 2/5)pi= (7pi/5).
 
  • #4
HallsofIvy
Science Advisor
Homework Helper
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sin-(cos(17pi/5))

cos=(x+n2pi)=cos(x)
It's not at all clear what you mean by "sin-(cos(17pi/5)". do you mean 'sine or cosine of that'? And, of course the "=" in "cos=" is a typo.

17/5= 3+ 2/5= 2+ (1+ 2/5). The "n" in "n2pi" is 1 and the "x" is (1+ 2/5)pi= (7pi/5).
 

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