Math, asked by AyushLokhande1706, 1 year ago

Lim x tends to 1-cos 4 theta /1-cos 6 theta

Answers

Answered by sprao534
22
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Answered by abhi178
21

answer is 4/9

we have to find \displaystyle\lim_{x\to 0}\frac{1-cos4\theta}{1-cos6\theta}

we know,

1 - cos2α = 2sin²α

so, 1 - cos4x = 1 - cos2(2x) = 2sin²(2x)

1 - cos6x = 1 - cos2(3x) = 2sin²(3x)

\displaystyle\lim_{x\to 0}\frac{2sin^2(2x)}{2sin^2(3x)}

= \displaystyle\lim_{x\to 0}\frac{sin^2(2x)}{sin^2(3x)}

= \frac{\displaystyle\lim_{x\to 0}\frac{sin^2(2x)}{(2x)^2}\times 4x^2}{\displaystyle\lim_{x\to 0}\frac{sin^2(3x)}{(3x)^2}\times 9x^2}

= 4x²/9x²

= 4/9

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