1. From the top of a lighthouse, 10m hight, the angle of depression of a boat is 20∘. How far is boat from the base of lighouse which is at sea-leve?
2. In the figure, A and B are two houses. Candy stands at C which is 80m away from A. She finds that ∠BAC =135∘and ∠ABC =20∘. Find the distance between the two houses.
有幾條數學唔識做........help
2007-12-05 1:27 am
回答 (1)
2007-12-05 2:45 am
✔ 最佳答案
1.tan20 = 10/xx = 27.5m
So the distance is 27.5m
2.∠ACB = 180 - 135 - 20 = 25
By sine formula,
AC/sin∠ABC = AB/sin∠ACB
80/sin20 = BC/sin25
BC = 98.9m
sine law你而家唔明,不過你又沒圖,我只有靠估去計數,所以我先用sine law,不過答案應該沒錯(如果我沒估錯幅圖既話)
收錄日期: 2021-04-21 17:51:55
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