Odpowiedź:
sinα = 3/5
sin²α = (3/5)² =9/25
Ponieważ sin²α + cos²α = 1 , więc sin²α = 1 - cos²α
1 - cos²α = 9/25
cos²α = 1 - 9/25 = 25/25 - 9/25 = 16/25
cosα = √(16/25) = 4/5
tgα = sinα/cosα = 3/5 : 4/5 = 3/5 * 5/4 = 3/4
7/3 - tgα = 7/3 - 3/4 = 28/12 - 9/12 = 19/12 = 1 i 7/12
