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Math Help - Trig bearing question (diagram attached)

  1. #1
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    Trig bearing question (diagram attached)

    An aeroplane flies horizontally due east at a constant speed of 240km/h. From a point P on the ground, the bearing of the plane at one instant is 311 degrees true north and 3 min later the bearing of the plane is 73 degrees T whilst its elevation then is 21 degrees. If h metres is the altitude of the plane, show that h=12000 sin 41 tan 21 cosec 58 and calculate h to the nearest metre.
    If a is the angle of elevation of the areoplane at the first point of observation, show that tana = sin 41 tan21 cosec17 and find a to the nearest minute
    DIAGRAM IS ATTACHEDDD
    (not 100% sure diagram is correct but relatively sure)
    PLEASE HELPPPP !!!!!
    thankyouuu !!
    Attached Thumbnails Attached Thumbnails Trig bearing question (diagram attached)-diagram.jpg  
    Last edited by mr fantastic; June 7th 2009 at 04:22 AM. Reason: Tidied up the post
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  2. #2
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    Quote Originally Posted by THSKluv View Post
    An aeroplane flies horizontally due east at a constant speed of 240km/h. From a point P on the ground, the bearing of the plane at one instant is 311 degrees true north and 3 min later the bearing of the plane is 73 degrees ...
    If h metres is the altitude of the plane, ....
    calculate h to the nearest metre.
    !!
    Questions such as this need to state the strict conditions for solution. With a dimension of 12000 metres the meaning of the word horizontal and vertical must be explicity stated. There is no place on the earth where the vertical h at AD is parallel to the vertical h at BC.

    If the word "horizontal" is supposed to mean a level flight or a straight line from A to B (not an arc) it should be so stated.

    There is a difference of over 3 metres between the value of h is a non earth situation and these conditions occuring somewhere on the earth.


    I know that's picky, but it could be a trick question.
    {I was tricked: You have a gun that fires a projectile with a muzzle velocity of 2000 miles per hour. Ignoring air resistance, when the projectile hits the ground it stops instantly at that point. How far would to have walk on a level surface to retrieve it. My answer was declared wrong. One might think that a level surface on the earth is flat, but you'd be wrong as I was. A level surface on the earth follows and arc. The curvature of the earth must be accounted for in the answer to the question.}
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  3. #3
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    uhhh okaii, yea i think it just means ..straight. i dont realli get the whole on earth thing, it was just a question from a textbook with a straightforward answer and diagram
    i dont think its meant to be a trick question...
    but uhh thanks for ur tip ?
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