# Math Help - Trig

1. ## Trig

If 2 sin(x-y)= sin(x+y), prove that tan x=3 tan y

2. Originally Posted by KingV15
If 2 sin(x-y)= sin(x+y), prove that tan x=3 tan y
$2sin(x-y)-sin(x+y)=0$

$[2sin(x)cos(y)-2cos(x)sin(y)]-[sin(x)cos(y)+cos(x)sin(y)] = 0$

$3sin(x)cos(y) = cos(x)sin(y)$

You should be able to finish this off now, just remember that $\frac{sin \theta}{cos \theta} = tan \theta$