Question

Tolong bantu jawab soal matematika trigonometri

Answer 1

Verified answer

Trigonometri

rumus jumlah

cos A  + cos B =  2 cos 1/2 (A+B) cos 1/2 (A - B)

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i) cos 6x + cos 2x = 2 cos 1/2 (6x+2x) cos 1/2(6x -2x)

cos 6x + cos 2x = 2 cos 1/2 (8x)  cos 1/2 (4x)

cos 6x + cos 2x =  2 cos 4x cos 2x

ii) cos 6x + cos 2x =  2 { 2 cos² 2x -  1) (cos 2x)

cos 6x + cos 2x =  2 ( 2 cos³ 2x - cos 2x)

cos 6x + cos 2x =  4 cos³ 2x -  2cos 2x