Cos 5π/12=1/4(√6-√2) buktikan bahwa

Mapel : Matematika
Kelas : X SMA
Bab : Trigonometri

Pembahasan :
Cos 5/12 phi = 1/4(√6 - √2)
Cos 75² = 1/4(√6 - √2)
Cos (90 - 15)° = 1/4(√6 - √2)
Sin 15° = 1/4(√6 - √2)
Sin (45 - 30)° = 1/4(√6 - √2)
Sin 45° Cos 30° - Cos 45° Sin 30° = 1/4(√6 - √2)
(1/2 √2)(1/2 √3) - (1/2 √2)(1/2) = 1/4(√6 - √2)
1/4 √6 - (1/4 √2) = 1/4(√6 - √2)
1/4(√6 - √2) = 1/4(√6 - √2)

Terbukti...