a) (P = 2 * (a + b) = 2 * (15,5 + 21,5) = 2 * 37 = 74)
б) (P = 2 * (a + b) => 40 = 2 * (a + 16,23) => 20 = a + 16,23 => a = 20 - 16,23 = 3,77)
в) (P = 2 * (a + b) => 48 = 2 * (11\frac{1}{4} + b) => 24 = 11,25 + b => b = 24 - 11,25 = 12,75)
Ответ:
a) P = 74
б) a = 3,77
в) b = 12,75