Mohon bantu 13 yang B ya:)

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interval [0°,π]

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sin 6x + sin 2x + sin 4x = 0

2 sin (6x + 2x)/2 cos (6x – 2x)/2 + sin 4x = 0

2 sin 4x cos 2x + sin 4x = 0

sin 4x (2 cos 2x + 1) = 0

sin 4x = 0 → x = 0°, 180°

2 cos 2x + 1 = 0

cos 2x = -1/2

2x = 120° + k.360°

x = 60° + k.180°

2x = 240° + k.360°

x = 120° + k.180°

k bilangan bulat

k = 0 → x = 60°, 120°

k = 1 → x = 240° , 300°

Nilai x yg memenuhi

0°, 60°, 120°, dan 180°