NCERT Class XI Mathematics - Trigonometric Functions - Solutions

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Question : 9
Total: 61
sin x =
3
5
, x lies in second quadrant.
Solution:  
sin x =
3
5
⇒ cosec x =
5
3

cos2x = 1 - sin2xcos2x = 1 -
9
25
=
16
25
⇒ cos x = ±
4
5

∴ cos x = -
4
5
[since x lies in second quadrant] ⇒ sec x =
5
4

∴ tan x =
sinx
cosx
=
3
4
⇒ cot x =
4
3

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