Hoe bewijs je dat sqrt (3) cos (x + pi / 6) - cos (x + pi / 3) = cos (x) -sqrt3sinx?

Hoe bewijs je dat sqrt (3) cos (x + pi / 6) - cos (x + pi / 3) = cos (x) -sqrt3sinx?
Anonim

# LHS sqrt3cos = (x + pi / 6) -cos (x-pi / 3) #

# = Sqrt3 cosx * cos (pi / 6) -sinx * sin (pi / 6) - cosx * cos (pi / 3) -sinx * sin (pi / 3) #

# = Sqrt3 cosx * (sqrt3 / 2) -sinx * (1/2) - cosx * (1/2) * -sinx (sqrt3 / 2) #

# = (3cosx-sqrt3sinx) / 2- (cosx-sqrt3sinx) / 2 #

# = (3cosx-sqrt3sinx-cosx sqrt3sinx +) / 2 #

# = (2cosx) / 2 = cosx = RHS #