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Math Help - coordinate geometry/circles/trigonometry

  1. #1
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    anfield road
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    coordinate geometry/circles/trigonometry

    a circle of a radius 6 units has its centre at the point (9,0). If the two tangents from the origin to the circle are inclined to the x axis at angles alpha and beta, find tan alpha and tan beta.
    in my answer tan alpha and tan beta are identical, but apparently thats wrong. ???
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  2. #2
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    maybe..... tg( alpha ) = - tg( beta )
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  3. #3
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    apparently, but why? i really dont get it. it wasnt hard for me to figure out that alpha = (2 x root of 5)/5 but why would beta be -? huh? its the same angle.
    thanks if sumwun could explain that...
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  4. #4
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    Look at this graph.
    Attached Thumbnails Attached Thumbnails coordinate geometry/circles/trigonometry-tan3.gif  
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