Limit value using definition of derivative

  • Thread starter karkas
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  • #1
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Homework Statement


I have encountered a limit that I wasn't really sure whether I was solving right, it's limit (a). I thought that I could find it considering a function f(x) (b) , find the derivative of that function and substitute x->1 so that I can find the value of the limit. Is this correct thinking???


Homework Equations



(a) lim(x->1) [ sin(x*pi/4) - sin(pi/4) ] / x-1

(b) f(x) = sin(x *pi/4) and so f ' (x) = pi/4 cos(x* pi/4)


The Attempt at a Solution


That would mean that (a) = f ' (1) = pi/4 * (√2)/2 , right?
 

Answers and Replies

  • #2
lurflurf
Homework Helper
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yes that is right
 
  • #3
132
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Ok, excellent, thanks!
 

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