Chunmaa asked in 科學及數學數學 · 1 decade ago

中三三角形的應用

在離地面25m的建築物上,分別以俯26度和33度觀察一燈柱的頂端和底部,求該燈柱高度。

2 Answers

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  • ?
    Lv 7
    1 decade ago
    Favorite Answer

    let x be the height of the lamp

    sin26=(25-x)/y

    sin33=25/y

    sin26/sin33=(25-x)/25

    0.44/0.54=1-x/25

    44/54==1-x/25

    x/25=1-44/54

    x/25=10/54

    x=10x25/54

    =4.63m

  • 1 decade ago

    Let x be the distance between 燈柱 and 建築物

    tan(90-33)=x/25

    x=25tan57

    Let y be the difference of height between 燈柱 and 建築物

    tan(90-25)=x/y

    y=25tan57/(tan65)

    結論:燈柱高度=25m-y=7.05m( 3 sign.)

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