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anonymous

  • one year ago

A television antenna 20 m high stands top of a house which 12 m high. At what distance from the base of the house will the antenna and the house subtend equal angle? A. 24 m* B. 15 m C. 31 D. 28 m the answer should be 24

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  1. welshfella
    • one year ago
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    |dw:1443354484410:dw|

  2. welshfella
    • one year ago
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    so you need to find D when x = y right?

  3. welshfella
    • one year ago
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    r u there?

  4. radar
    • one year ago
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    I'm here, but it is not my problem @welshfella, was hoping you would provide some more steps (for my own edification lol).

  5. anonymous
    • one year ago
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    i have tried to solve it but i cant get 24m

  6. anonymous
    • one year ago
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    we have the same drawing but still i cant get the answer

  7. welshfella
    • one year ago
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    lol ok well i think we can use the double angle formula. write y for x:- so tan 2y = 2 tan y -------- 1 - tan^2 y and tan y 2y = 32/D and tan y = 12 / D

  8. welshfella
    • one year ago
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    * that's tan 2y = 32 / D

  9. anonymous
    • one year ago
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    what should i do next?

  10. welshfella
    • one year ago
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    plug tan 2y = 32/D and tan y = 12/D into the above identity and solve for D

  11. IrishBoy123
    • one year ago
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    @welshfella big fat Celtic Congrats, mate!!!

  12. welshfella
    • one year ago
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    |dw:1443355391490:dw|

  13. welshfella
    • one year ago
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    HaHa Thanks Irish boy. We beat the English!!!!

  14. welshfella
    • one year ago
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    @Jluz - can you solve that one for D?

  15. anonymous
    • one year ago
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    i used my calcu shift solve but it doesnt result in to 24m

  16. radar
    • one year ago
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    Yes is does, thanks @welshfella

  17. anonymous
    • one year ago
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    @radar i cant get it my answer is 12.38

  18. welshfella
    • one year ago
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    yea I get the same as you JLuz Maybe i made a mistake somewhere....

  19. radar
    • one year ago
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    |dw:1443355873893:dw| Do you follow this far @JLuz

  20. anonymous
    • one year ago
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    yes

  21. radar
    • one year ago
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    |dw:1443355996631:dw| How about to this?

  22. welshfella
    • one year ago
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    yea it does work out to 24

  23. radar
    • one year ago
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    |dw:1443356181782:dw| and then to this?

  24. welshfella
    • one year ago
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    gotta go ul leave you in capable hands of radar

  25. radar
    • one year ago
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    Can you take it to "24" ?

  26. anonymous
    • one year ago
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    i wil solve

  27. radar
    • one year ago
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    Good As you see, I just used "cross multiplication" of the fraction.

  28. anonymous
    • one year ago
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    wow yea

  29. radar
    • one year ago
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    Good luck with your studies.

  30. anonymous
    • one year ago
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    is results to 24

  31. anonymous
    • one year ago
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    i have a question

  32. anonymous
    • one year ago
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    why does she uses double angle formula??

  33. radar
    • one year ago
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    Go ahead, but I think @welshfella has left, he had the incite for the solution.

  34. radar
    • one year ago
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    Because the angle to the top of the antenna is equal to the sum of the two equal angles to the top of the house and the angle from the top of the house to the top of the antenna. In the drawing the big angle is equal to the sum of X and Y and we are told that they are equal .......... hence "double angle"

  35. radar
    • one year ago
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    |dw:1443356763926:dw|

  36. radar
    • one year ago
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    I was messing around trying to use the law of sines and wasn't getting anywhere, I think that double angle approach was a good idea.

  37. anonymous
    • one year ago
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    i was trying to analyze your explanation haha

  38. anonymous
    • one year ago
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    nosebleed haha

  39. radar
    • one year ago
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    The use of the double angle identity was a wise choice. You will run into that identity in Trig' maybe you already have studied the trigometric identities.

  40. anonymous
    • one year ago
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    ok radar thank you for your big help

  41. anonymous
    • one year ago
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    it is a big help in my studies

  42. radar
    • one year ago
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    Good luck

  43. radar
    • one year ago
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    I think you will do well, because you knew what the answer was, but you needed to know "how" or verify that it was indeed a correct answer, that is a good trait.

  44. anonymous
    • one year ago
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    as well as to @welshfella

  45. anonymous
    • one year ago
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    thanks @welshfella

  46. welshfella
    • one year ago
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    yw

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