buktikan identitas trigonometri (sin x +cos x)²-(sin x -cos x)²=4sin x.cos x
Matematika
Sir01
Pertanyaan
buktikan identitas trigonometri (sin x +cos x)²-(sin x -cos x)²=4sin x.cos x
1 Jawaban
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1. Jawaban Robinn
= (sinx + cosx)² - (sinx - cosx)²
= sin²x + 2sinxcosx + cos²x - (sin²x - 2sinxcosx + cos²x)
= 1 + 2sinxcosx - (1 - 2sinxcosx)
= 1 + 2sinxcosx - 1 + 2sinxcosx
= 4sinxcosx