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Question about 30:60:90 (noob)

  1. Aug 16, 2011 #1
    Im watching one of khan's videos:
    http://www.youtube.com/watch?v=Qwet4cIpnCM&feature=player_embedded#at=468

    And he's using the pythagorean theorem to solve height of a 30-60-90 triangle.
    Prior to everything, I think I have a good understanding on how it all works, however, I still don't feel like I understand it fully.

    From what I understand, pythagorean theorem's formula is: base^(2) x height^(2) = hypotenuse^(2).

    Now if you watch the video and skip to the 8:00 mark, everything seems to make sense to me except the part where he adds '4' as the denominator under h^(2), nor do I understand how he got 'A=h^(2)(1 - 1/4).
    Where did the 4 come from?

    Sorry if this is an obvious question, Im self teaching and really just want to learn and fully understand it.

    Thanks =)
     
  2. jcsd
  3. Aug 16, 2011 #2
    From the video at the 8 min mark,

    [1/2*h]^2 = [1/2]^2*[h]^2 = 1/4*h^2 = h^2/4

    Does this help?
     
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