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Evaluate: limx→01-cos2xx2

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Question

Evaluate: `lim_(x -> 0) (1 - cos 2x)/x^2`

Sum
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Solution

Given that `lim_(x -> 0) (1 - cos 2x)/x^2`

= `lim_(x -> 0) (2 sin^2x)/x^2`  .......[cos 2x = 1 – 2 sin2x]

= `lim_(x -> 0) 2(sin x/x)^2`

= `2 xx 1`

= 2   .....`[because  lim_(x -> 0) sinx/x = 1]`

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Chapter 13: Limits and Derivatives - Exercise [Page 240]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 13 Limits and Derivatives
Exercise | Q 17 | Page 240

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