Pertanyaan

Buktikan identitas berikut. a. cos ( α + β ) ⋅ cos ( α − β ) + 1 = cos 2 α + cos 2 β

Buktikan identitas berikut.

a. $cos (α + β) \cdot cos (α - β) + 1 = cos^{2} α + cos^{2} β$

W. Lestari

Master Teacher

Mahasiswa/Alumni Universitas Sriwijaya

Jawaban terverifikasi

Jawaban

terbukti bahwa .

terbukti bahwa cos space open parentheses straight alpha plus straight beta close parentheses times cos space open parentheses straight alpha minus straight beta close parentheses plus 1 equals cos squared space straight alpha plus cos squared space straight beta

cos space open parentheses straight alpha plus straight beta close parentheses times cos space open parentheses straight alpha minus straight beta close parentheses plus 1 equals cos squared space straight alpha plus cos squared space straight beta

Pembahasan

Ingat kembali: Akan dibuktikan . Maka: Jadi, terbukti bahwa .

Ingat kembali:

Akan dibuktikan cos space open parentheses straight alpha plus straight beta close parentheses times cos space open parentheses straight alpha minus straight beta close parentheses plus 1 equals cos squared space straight alpha plus cos squared space straight beta . Maka:

Jadi, terbukti bahwa cos space open parentheses straight alpha plus straight beta close parentheses times cos space open parentheses straight alpha minus straight beta close parentheses plus 1 equals cos squared space straight alpha plus cos squared space straight beta .