How do you find #lim theta costheta# as #theta->oo#?

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Answer 1 · 2017-03-07T18:53:57

DNE

#lim_(theta to oo) theta cos theta#

We know that: #-1 le cos theta le 1#

So:

#-theta le theta cos theta le theta#

And:

#lim_(theta to oo) -theta le lim_(theta to oo) theta cos theta le lim_(theta to oo) theta#

#implies -oo le lim_(theta to oo) theta cos theta le oo#

Maybe it's stating the obvious but because cosine is periodic, there is no limit.