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  1. The value of
    sin θ - 2sin3 θ
    		 is
    2 cos3 θ - cosθ
    1. sin θ
    2. cos θ
    3. tan θ
    4. cot θ
Correct Option: C

Expression

=
sinθ - 2sin3θ
2cos3θ -cosθ

=
sinθ ( 1 - 2sin2θ)
cosθ (2cos2θ - 1)

=
sinθ
 .
(1 - 2 (1 - cos²θ)))
cos θ(2cos²θ - 1)

= tan θ
(1 + 2 cos² θ - 2)
(2 cos² θ - 1)

= tan θ.
2 cos²θ - 1
= tan θ
2 cos²θ - 1


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