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唔識做2題中3數學題
2008-05-12 4:36 am
回答 (2)
2008-05-12 4:56 am
✔ 最佳答案
第1題AB = BD = 6 cm
AD = 4 cm
因為ADC是等腰三角形 AD = DC = 4 cm
BC = BD + DC = 10 cm
第2題
角CBD = 180 - a
角BCD = 180 - b
(180-a) + ( 180-b) + c = 180
180-a+180-b+c=180
a+b-c=180
2008-05-12 8:28 am
補充第1題
因為ABD是等腰三角形,
所以
角BDA = 角BAD = (180-40)/2 = 70
角ADC = 180 - 角BDA = 180-70 = 110
角ACD = (180 - 角ADC)/2 = (180 – 110)/2 = 35度
由B劃一條垂直線到AD, 把 角B分為兩個 20度.
AD = 2 X BD sin20 = 2 X 6 X sin20 = 4.10 cm
BC = BD + DC = BD + AD = 6 cm + 4.10 cm = 10.10 cm
因為ABD是等腰三角形,
所以
角BDA = 角BAD = (180-40)/2 = 70
角ADC = 180 - 角BDA = 180-70 = 110
角ACD = (180 - 角ADC)/2 = (180 – 110)/2 = 35度
由B劃一條垂直線到AD, 把 角B分為兩個 20度.
AD = 2 X BD sin20 = 2 X 6 X sin20 = 4.10 cm
BC = BD + DC = BD + AD = 6 cm + 4.10 cm = 10.10 cm
收錄日期: 2021-04-25 16:40:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080511000051KK02565