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Tamil Nadu Board of Secondary EducationHSC Science Class 11

If y = 2sinα1+cosα+sinα, then prove that 1-cosα+sinα1+sinα = y - Mathematics

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Question

If y = `(2sinalpha)/(1 + cosalpha + sinalpha)`, then prove that `(1 - cosalpha + sinalpha)/(1 + sinalpha)` = y

Sum
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Solution

`(2sinalpha)/(1 + cosalpha + sinalpha) = (2sinalpha)/((1 + sinalpha) + cosalpha)`

= `(2sinalpha)/((1 + sin alpha) + cos alpha) xx ((1 + sinalpha) - cosalpha)/((1 + sinalpha) - cosalpha)`

y = `(2sinalpha(1 - cosalpha + sinalpha))/((1 + sinalpha)^2 - cos^2alpha)`

= `(2sinalpha(1 - cosalpha + sinalpha))/(1 + 2sinalpha + sin^2alpha - cos^2alpha)`

= `(2sinalpha(1 - cosalpha + sinalpha))/(1 + 2sinalpha + sin^2alpha - (1 - sin^2alpha))`

= `(2sinalpha(1 - cosalpha + sinalpha))/(1 + 2sinalpha + sin^2alpha - 1 - sin^2alpha)`

= `(2sinalpha(1 - cosalpha + sinalpha))/(2sinalpha + 2sin^2alpha)`

= `(2sinalpha(1 - cosalpha + sinalpha))/(2sinalpha(1 + sinalpha))`

y = `(1 - cosalpha + sinalpha)/(1 + sinalpha)`

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A Recall of Basic Results
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Chapter 3: Trigonometry - Exercise 3.1 [Page 92]

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Samacheer Kalvi Mathematics - Volume 1 and 2 [English] Class 11 TN Board
Chapter 3 Trigonometry
Exercise 3.1 | Q 6 | Page 92
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