№26.13(а),

№26.16(б),

№26.17(б)

26.13 tg(π-t) / cos(π+t) * sin 3π/2+t) / tg(3π/2+t) = -tg(t) / - cos(t) * - cos(t) / - ctg(t) = tg (t) / ctg (t) = tg^(t)

26.16 cos125*cos5 + sin55*cos85 = cos (180-55) * cos (90 - 85) * sin55 cos85 = - cos55 * sin85 - cos55 * sin95 = sin (55 - 85) = - sin30 = - 1/2