Diketahui Cos 2A=⅓dengan Sudut Lancip. Tentukan nilai tan A

jawab

cos 2A = 1/3
1 - 2 sin² A = 1/3
- 2 sin² A = =- 2/3
sin² A = 1/3
sin A = √(1/3) 

cos A= √( 1 - sin² A) = √(1 - 1/3)= √(2/3)

tan A  = sin A/cos A = √(1/3) / √(2/3) = √(1/2)
tan A = 1/2 √2