Question

Nilai cos 15, pakai cara!

Answer 1

Cos 15 = cos (45 - 30) ⇒ angka lain juga bisa asalkan sudut istimewa

cos (45 - 30) = cos 45 cos 30 + sin 45 sin 30
cos 15 = 1/2√2 x 1/2√3 + 1/2√2 x 1/2
cos 15 = 1/4 √6 + 1/4 √2
cos 15 = (√6 + √2) /4