sin(x + ) + sin(x - ) = -1
sin(x)cos( ) + cos(x)sin( ) + sin(x)cos( ) - cos(x)sin( ) = -1
2nd and 4th terms on the left cancel, 1st and 3rd terms are the same:
2sin(x)cos( ) = -1
sin(x)cos( ) =
and since cos( ) =
sin(x)· =
Multiply both sides by 2
sin(x)·√2 = -1
sin(x) =
sin(x) = ·
sin(x) =
x = ,
Edwin