Ответы и объяснения

2013-12-25T22:28:58+04:00
S = √(p(p-a)(p-b)(p-c)), p = (a + b + c)/2 = 21.
S = √(21 * 8 * 7 * 6) = 84;
S = 1/2 BD * AC;
BD = 2S/AC = 2 * 84 / 14 = 12