Odpowiedź:
sinα=3/5 ; α ∈ ( 90° ,180°)
W tym przedziale mamy:
sinα = sinα
cosα = - cosα
tgα = - tgα
ctgα = - ctgα
--------------------------
sinα = 3/5
sin²α = (3/5)²= 9/25
1- cos²α = 9/25
cos²α= 1- 9/25 = 25/25- 9/25 = 16/25
cosα = √(16/25) = 4/5
cos(180°- α) = - cosα = - 4/5
tgα = sinα/cosα = 3/5 :4/5 = 3/5 * 5/4 = 3/4
tg(180 - α) = - tgα = - 3/4
ctgα = 1/tgα= 4/3
ctg(180° - α) = - ctgα = - 4/3= - 1 1/3
