2Sinx / Cos3x = tan3x - tanx

Answers 2

Answer:= 2sin(x)

Step-by-step explanation:

2sin(x)/cos(3x) = tan(3x) - tan(x)

Let's try to prove that 2sin(x) = sin(3x) - tan(x)cos(3x).

Using the identities sin(3x) ? 3sin(x) - 4sin³(x) and cos(3x) ? 4cos³(x) - 3cos(x),

sin(3x) - tan(x)cos(3x) = 3sin(x) - 4sin³(x) - tan(x)(4cos³(x) - 3cos(x))

                                 = sin(x)(3 - 4sin²(x) - (4cos²(x) - 3))

                                 = sin(x)(6 - 4(sin²(x) + cos²(x)))

                              = 2sin(x).

(The above is simpler than using the standard identity that gives tan(3x) in terms of tan(x).)

2sin(x)/cos(3x) = tan(3x) - tan(x)

Let's try to prove that 2sin(x) = sin(3x) - tan(x)cos(3x).

Using the identities sin(3x) ? 3sin(x) - 4sin³(x) and cos(3x) ? 4cos³(x) - 3cos(x),

sin(3x) - tan(x)cos(3x) = 3sin(x) - 4sin³(x) - tan(x)(4cos³(x) - 3cos(x))

= sin(x)(3 - 4sin²(x) - (4cos²(x) - 3))

= sin(x)(6 - 4(sin²(x) + cos²(x)))

= 2sin(x).

(The above is simpler than using the standard identity that gives tan(3x) in terms of tan(x).)

hope this will helpful for you

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