Sendo cos de alfa = 2/3, calcule sen de alfa e tg de alfa?

Sen²α + cos²α = 1, p/ cosα = 2/3
sen²α +(2/3)² = 1
sen²α = 1 - 4/9 => sen²α = 5/9 => senα = √5/√9 => senα = √5/3

tgα = senα/cosα, p/ senα = √5/3 // cosα = 2/3
tgα = √5/3 / 2/3 => tgα = √5/3.3/2 => tgα = √5/2​