Відповіді АЛГЕБРА: 10.18

10.18

1) ctgα = –17

tgα = 1ctgα = –7

2) sinα = 0,8 π2 < α < π

cosα = ± 1- sin2α

α – II чв. cosα < 0

cosα = – 1- 0,82 = –0,6.

tgα = sinαcosα = 0,8-0,6 = –43

3) sinφ – ? tgφ – ? ctgφ – ?.

cosφ = –1213, π < φ < 3π2

φ – III чв.

sinφ < 0 sinφ = –1- cos2φ

sinφ = –1-(-1213)2 = –1- 144169 = –25169 = –513

tgφ = sinφcosφ = -513-1213 = 512

cngφ = 125

4) sinβ = –2425 3π2 < β < 2π

β – IV чв. sinβ < 0, a cos β > 0

cosβ = 1- sin2β = 1-(-2425)2 = 725

tgβ = sinβcosβ = -2425725 = –247

ctgβ = 1tgβ = –724