Question

Nyatakan sebagai jumlah atau selisih kosinus : cos 4x cos 3x

Answer 1

Verified answer

TriGonoMetRi

2 cos a cos b = cos (a + b) + cos (a - b)

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cos 4x cos 3x
= 1/2 (cos (4x + 3x) + cos (4x - 3x)
= 1/2 (cos 7x + cos x) ✔