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sin a; cos a; tg a; ctg a

1]cos a = - 2/3

2]sin a = 1/4

1. sin α = √ (1-cos²α) = √ (1 - 4/9) = √ (5/9) = √5 / 3

tg α = sin α / cos α = √5/3 : (-2/3) = - √5/2

ctg α = 1 / tg α = 1 / (-√5/2) = - 2 / √5 = - 2√5 / 5

2. cos α = √ (1-sin²α) = √ (1-1/16) = √ (15/16) = √15 / 4

tg α = 1/4 : √15/4 = 1/√15 = √15 / 15

ctg α = 1 / 1/√15 = √15