BUTUH SEKARANG !!!

Sin(x) + sin(2x) > sin(3x)
sin(x) + sin(2x) – sin(3x) > 0
sin(x) – sin(3x) + sin(2x) > 0
2 cos(2x) sin(-x) + 2 sin(x) cos(x) > 0
-2 cos(2x) sin(x) + 2 sin(x) cos(x) > 0
2 sin(x) (cos(x) – cos(2x)) > 0
2 sin(x) (cos(x) – (2 cos²(x) – 1)) > 0
2 sin(x) (-2 cos²(x) + cos(x) + 1) > 0
2 sin(x) (-cos(x) + 1) (2 cos(x) + 1) > 0

⇒ pembuat nol:
cara1:
2 sin(x) = 0
sin(x) = 0
x = 0° , 180° , 360°

cara2:
-cos(x) + 1 = 0
cos(x) = -1
x = 0° , 360°

cara3:
2 cos(x) + 1 = 0
2 cos(x) = -1
cos(x) = -1/2
x = 120° , 240°

⇒ Jadi, Himpunan penyelesaiannya:
HP : {x | 0° < x < 120° , 180° < x < 240°}

Jadiin Sebagai Solusi Terbaik ^^