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CLASS_11_MATHS_SOLUTIONS_NCERT

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Class XI Chapter 3 – Trigonometric Functions Maths<br />

______________________________________________________________________________<br />

Question 8:<br />

Prove that<br />

Solution 8:<br />

L.H.S.<br />

<br />

<br />

<br />

cos x<br />

cos x<br />

cot<br />

<br />

<br />

sin x<br />

cos<br />

x<br />

2 <br />

<br />

<br />

xcos<br />

x<br />

cos<br />

<br />

<br />

<br />

sin <br />

xcos<br />

x<br />

2 <br />

cos<br />

xcos<br />

x<br />

sin<br />

xsin<br />

x<br />

cos<br />

sin<br />

2<br />

2<br />

2<br />

cot x<br />

= R.H.S.<br />

x<br />

x<br />

2<br />

x<br />

Question 9:<br />

3<br />

3<br />

<br />

<br />

cos xcos 2<br />

x cot x cot 2<br />

x 1<br />

2<br />

<br />

2<br />

<br />

<br />

<br />

Solution 9:<br />

L.H.S. =<br />

<br />

3 <br />

cos cos 2 cot 3 <br />

<br />

x x x cot 2<br />

x<br />

2<br />

<br />

2<br />

<br />

<br />

<br />

<br />

sin x cos x tan x cot x<br />

sin x cos x<br />

sin<br />

xcos<br />

x<br />

<br />

cos<br />

x sin x <br />

2 2<br />

sin<br />

x<br />

cos x<br />

sin xcos<br />

x <br />

sin xcos<br />

x<br />

<br />

<br />

<br />

<br />

= 1 = R.H.S.<br />

<br />

<br />

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