1) sin a = -5/13 , 3π/2 < a < 2π
cos a = √(1 - (-5/13)²) = √(1 - 25/169) = √(144/169) = 12/13
tg a = sina / cosa = (-5/13)/(12/13) = -5/12
ctg a = 1/tg a = -12/5
2) cos a = -8/17 , π < a < 3π/2
sin a = - √(1 - (-8/17)²) = - √(1 - 64/289) = - √(225/289) = - 15/17
tg a = sin a / cos a = (-15/17)/(-8/17) = 15/8
ctg a = 1/tg a = 8/15
3) tg a = 8/15 , π < a < 3π/2
сtg a = 1/tg a = 15/8
cos a = - √(1/(1 + tg²a)) = -√(1/(1 + 64/225)) = -√(1/289/225) = -15/17
sin a = -√(1 - 225/289) = -√(64/289) = - 8/17
4) ctg a = -7/24 , 3π/2 < a < 2π
tg a = 1/ctg a = - 24/7
sin a = - √(1/(1 + ctg²a)) = -√(1/(1+49/576)) = -√(1/625/576) = -24/25
cos a = √(1 - (576/625)) = √(49/625) = 7/25