cos 4x + cos 2x = 0 untuk 0
Matematika
aldi1246
Pertanyaan
cos 4x + cos 2x = 0 untuk 0<x<2phi
1 Jawaban
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1. Jawaban nasril8
cos 4x + cos 2x = 0
cos (2x + 2x) + cos 2x = 0
2cos^2 2x - 1 + cos 2x = 0
2cos^2 2x + cos 2x - 1 = 0
(2cos 2x - 1 ) (cos 2x + 1 ) = 0
2cos 2x - 1 = 0
2cos 2x = 1
cos 2x = 1/2
cos 2x = cos 60, 120
2x = 60, 120 + k.360
x = 30+k.180 , x = 60 + k.180
x = 30, 60, 210, 240
cos 2x + 1 = 0
cos 2x = -1
cos 2x = cos 180
2x = 180
x = 90 +k.180
x = 90, 270
HP = { 30°, 60°, 90°, 210°, 240°, 270° }