a) π/2<t<π - 2-ая четвертьcost - " - "tgt и ctgt - " - "cost = -√(1-(4/5)²) = - √(1 - 16/25) = - √9/25 = -3/5tgt = sint / cost = 4/5 : (-3/5) = -4/3ctgt = 1/tgt = -3/4б) 0<t<π/2 - 1-ая четвертьcost , tgt, ctgt - " + "cost = √(1-(5/13)²) = √(1- 25/169) = √(144/169) = 12/13tgt= 5/13 : (12/13)=5/12ctgt = 12/5 в) -π/2<t<0 - 4-ая четвертьcost - " + "tgt, ctgt - " - "cost = √(1-(-0.6)²) = √(1-0.36) = √0.64 = 0.8tgt = -0.6 / 0.8 = - 6/8 = - 3/4ctgt = - 4/3г) π<t<3π/2 - 3-я четвертьcost - " - "tgt, ctgt - " + "cost = - √(1-(-0.28)²) = - √0.9216 = - 0.96tgt = -0.28 / (-0.96) = 28/96 = 7/24ctgt = 24/7 = 3 ³/₇