Question

реши уравнение: sin 12x+ sin 4x=0

Answer 1

sin 12x+ sin 4x=0 
2sin (12x+ 4x)/2 *cos(12 x -  4x)/2 = 0 
2*sin8x * cos 4x = 0 

sin8x = 0 
8x = pik
x = pik/8, k ∈ Z

cos4x = 0 
4x = pi/2 + pik
x = pi/8 + pik/4 , k ∈ Z