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  1. If cosx = –
    3
    and p < x <
    , then the value of sin 2x will be
    52
    1. 12
      25
    2. 1
      15
    3. 24
      25
    4. 5
      26
Correct Option: C

Here,

cosx = –
3
and p < x <
52

⇒ x lies in third quadrant, and we know that in third quadrant only tan and cot are positive.
Consider right angled ∆ABC,

Using pythagoras theorem,
AC² = AB² + BC²
⇒ 5² = (–3)² + BC²
16 = BC²
⇒ BC = 4
We know that,
sin2A = 2sinA × cosA
⇒ sin2x = 2 × sinx× cosx
= 2 ×
- 4
×
- 3
55

=
24
25

∵ Here, sinq is –ve



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