Поскольку cos(alpha) = 0.8 и alpha = 0, то sin(alpha) = 0 и ctg(alpha) = 1 / tan(alpha) = 1 / tan(0) = 1 / 0 = бесконечность.
Поскольку cos(alpha) = 0.8 и alpha = 0, то sin(alpha) = 0 и ctg(alpha) = 1 / tan(alpha) = 1 / tan(0) = 1 / 0 = бесконечность.