jika cos 4A = [tex] \frac{1}{4} [/tex] maka cos 8A + cos 16 A =
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Pertanyaan
jika cos 4A = [tex] \frac{1}{4} [/tex] maka cos 8A + cos 16 A =
1 Jawaban
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1. Jawaban dhikboss
cos 8A = 2 cos² 4A - 1
= [tex]2. (\frac{1}{4})^{2}-1 [/tex]
= [tex] -\frac{7}{8} [/tex]
cos 16A = 2 cos² 8A - 1
= [tex]2. (-\frac{7}{8})^{2} -1[/tex]
= [tex] \frac{17}{32} [/tex]
cos 8A + cos 16 A = [tex] -\frac{7}{8} + \frac{17}{32} = \frac{-28+17}{32} = -\frac{11}{32} [/tex]