设 3分之a = 4分之b = 2分之c = k则 a = 3k ,b = 4k ,c = 2kab + bc + ac = 5212k² + 8k² + 6k² = 5226k² = 52k² = 2k = √2 或 k = -√2因为 a,b,c都是正数所以 k > 0所以 k = √2 所以 a...