Trig identity

  • #1
187
0

Main Question or Discussion Point

no clue how to start this:

show

sin 3x = 3 sin x - 4 sin^3 x
 

Answers and Replies

  • #2
How to start this: sin(3x) = sin(2x+x)
 
  • #3
187
0
right so after doing this i get

sin 3x = sin2x(cos x) + (cos2x)(sin x)

whats next
 
  • #4
sin(2x)=...?
cos(2x)=...?
 
  • #5
187
0
thanks for the help i got this and the others
 

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