Diketahui sin a = 1/5, a sudut lancip. Nilai cos 2a = ...

TriGonoMetRi

sin a = 1/5

cos 2a
= 1 - 2 sin² a
= 1 - 2 (1/5)²
= 1 - 2/25
= (25 - 2)/25
= 23/25

abaikan yang dicoreret yaaaa