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iamthegelo
Oct24-09, 05:54 AM
1. The problem statement, all variables and given/known data

By using trig formulas show that,

sin(2x + pi/3) = sin(2x) + sin(2(x+pi/3))

2. Relevant equations

Trig Identities

3. The attempt at a solution

I've used double angle formulas, sin(a+b) formulas, I just can't seem to get it.

CompuChip
Oct24-09, 06:33 AM
It does look like a case for sin(a + b). Can you show us what went wrong when you simply apply the identity for sin(a + b) = sin(a) ... + ... to sin(2x + pi/3) ?

lurflurf
Oct24-09, 02:14 PM
write (for the left hand side)
sin(2x + pi/3)=[sin(2x + pi/3)-sin(2x +2pi/3)]+sin(2(x + pi/3))
recall the identity for
sin(a)-sin(b)