math!!!!!!!!!!!!!!!!!!!!!!!!
回答 (1)
2008-01-09 4:05 am
✔ 最佳答案
角DCA = 角DAC = a角BAC = 90度
(設 角DAB = b, 角ABD 也是 b, 由三角形內角和得 2a + 2b = 180)
則 sina = AB / BC = 6 / (5+5) = 3/5
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