Math, asked by Anonymous, 9 months ago

 \huge{\underline{\overline{\mathtt{\mid{Evaluate:-}\mid}}}}
limit x tends to 0
 \huge \frac{ \ \cos2x - 1 }{ \cos \: x - 1 }

Answers

Answered by RvChaudharY50
179

Question :------

  • limit x 0
  •  \huge \frac{ \ \cos2x - 1 }{ \cos \: x - 1 }

Formula used :------

  • cos2x = 1 - 2 sin²x
  • sin2x = 2 sinx × cosx
  • cox0° = 1
  • L hospital rule ....

Solution :-----

According to L hospital rule we know that,,

limit x → 0

\huge\frac{f(x)}{g(x)}

= limit x → 0

\huge\frac{f'(x)}{g'(x)}

so,

limit x → 0

 \huge \frac{ \ \cos2x - 1 }{ \cos \: x - 1 }

\red{\boxed\implies} \: lim \: x \iff0 =  \frac{ - sin2x}{ - sinx}  \\  \\ \red{\boxed\implies} \: lim \: x \iff0 =  \:  \frac{  \cancel- 4 \cancel{sinx}cosx}{ \cancel{ - sinx}}  \\  \\ \red{\boxed\implies} \: lim \: x \iff0 =  \: 4cosx \\  \\ now \: since \: cosx \: at \: x \:  = 0 \: is \: 1.. \\  \\  \\  \\ so \:  \\  \\  \\ \red{\boxed\implies} \: lim \: x \iff0 =  \: 4cosx \:  =  \red{\large\boxed{\bold{4}}}

so, value of given date is 4 ....

(Hope it helps you) ...

Answered by Anonymous
10

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