Question
Solve the equation sin3x+sins=0,for value of x from -180°to180°, inclusive.
Answers
oobleck
sin3x+sinx = 0
since sin3x is a cubic function of sinx, that looks hard.
But your addition formula says that
sin3x + sinx = 2 sin2x cosx
So now you just have to solve
sin2x cosx = 0
2x = kπ
x = kπ + π/2
Looks like you want -180, -90, 0, 90, 180
since sin3x is a cubic function of sinx, that looks hard.
But your addition formula says that
sin3x + sinx = 2 sin2x cosx
So now you just have to solve
sin2x cosx = 0
2x = kπ
x = kπ + π/2
Looks like you want -180, -90, 0, 90, 180