A D.

asked • 09/23/21

Prove that limit X approaches a from the right : cos x= cos a

Paul M.

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You need to specify what assumptions you are allowed. cos is continuous everywhere...which you can show using the Taylor series or you can use the formula for cos(x+h).
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09/25/21

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Katya S. answered • 09/25/21

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This question has been answered before on Wyzant by Andy C. (answered • 10/15/18)

I quote:

Difference quotient

{ cos(a+x)-cos(x)} / (a+x-x)

cos(a+x)-cos(x) / a = 0

so the derivative exists which guarantees continuity.

So cos x = cos a as x--> a


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