Question

 show that sin3x=3sinx -4sinx

Answer 1

$\huge{Hey Mate!!!}$

Here is the answer to your question.

 

sin3x = sin (2x + x)

= sin2x cos x + cos2x sinx

= 2 sinx cosx × cosx + (1 – 2 sin2x) sinx  (sin2x = 2 sinx cosx, cos2x = 1 – 2 sin2x)

= 2 sinx cos2x + sinx – 2 sin3x

= 2 sinx (1 – sin2x) + sinx – 2 sin3x

= 2 sinx – 2 sin3x + sinx – 2 sin3x

= 3 sinx – 4 sin3x

 

Thus, sin 3x = 3 sinx – 4 sin3x

 

Cheers!!!

Answer 2

$\huge{Hello Friend}$

The answer of u r question is..✌️✌️

Ans:✍️✍️✍️✍️✍️✍️✍️

Sin 3 x = Sin (2x + x)

= Sin 2 x cos x + cos 2 x Sin x

=2 sinx cosx + cosx +(1-2 sin2x) sinx (sin 2 x = 2 sinx cos x cos 2 x=1-2sin 2 x)

= 2 sin x cos 2x + sin x - 2 sin 3x

= 2 sin (1-sin 2 x)+sin x -2 sin 3 x

= 2 sin x -2 sin 3x + sinx -2sin3x

= 3 sinx - 4 3sinx


Thank you..❣️❤️