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標題:

3條f.2升f.3數學(畢氏定理)!!(10點!!)

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最佳解答:

您好，我是 lop****** ，高興能解答您的問題。 (1) x = √[132-(3+7)2] = √(169-100) = √69 y = √[32+ (√69)2] = √(9+69) = √78 (2) 122+ BC2= AC2 144 + (AC/4)2= AC2 144 + AC2/16 = AC2 2304 = 15AC2 AC2= 153.6 AC = 16√(3/5) (3a) 周界 = PQ + QR + PR = 2√(62/2) + 6 = 2√18 + 6 = (6√2 + 6) cm (3b) 面積 = PQ × QR / 2 = √(62/2) × √(62/2) / 2 = (18/2)/2 = 9/2 cm2 2011-08-30 18:31:29 補充： corr. (3b) 面積 = PQ × QR / 2 = √(62/2) × √(62/2) / 2 = (36/2)/2 = 18/2 = 9 cm2

其他解答:

你好，我是STY，我的解答如下： 1) AB^2 + BD^2 = AD^2 AB^2 + (3 + 7)^2 = 13^2 AB^2 + 100 = 169 AB^2 = 69 AB = sqrt69 AB^2 + BC^2 = AC^2 (sqrt69)^2 + 3^2 = y^2 y^2 = 9 + 69 = 78 y = sqrt78 所以，x = sqrt69, y = sqrt78 2) BC = AC/4 AC = 4 * BC AB^2 + BC^2 = AC^2 144 + BC^2 = 16 * BC^2 15 * BC^2 = 144 BC^2 = 48/5 BC = 4sqrt15 / 5 AC = 4sqrt15 / 5 + 20 / 5 = (4sqrt15 + 20) / 5 (按cal機) 3a) PQ^2 + QR^2 = PR^2 2PQ^2 = 36 PQ^2 = 18 PQ = sqrt18 = 3sqrt2 周界 = (6sqrt2 + 6) cm 面積 = (3sqrt2)^2 / 2 = 9 cm^2 BY STY~