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Pythagorean Theorem

  1. Mar 1, 2006 #1
    Hey everyone,
    I understand a2+b2=c2, but I have trouble figuring out which side is which in problems like these:
    http://img417.imageshack.us/img417/8238/py8gu.png [Broken]

    Can someone explain?
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Mar 1, 2006 #2
    You can't do the first one without knowing any angles.

    On the second one, I think you drew it incorrectly because you can tell that it is two. However, if it was on the width instead of length, then you would do x^2+2^2=4^2.

    Remember, the pythagorean theorem only works with right triangles. However, you can often cut something into a right triangle. It would be better if you could draw an image of an actual example from your book or whatever.
  4. Mar 1, 2006 #3
    pythagorean theory only works for right triangles. for the first triangle you would have to draw an altitude right down the middle to make two right triangles. Don't forget to cut x in half also.
    Last edited: Mar 1, 2006
  5. Mar 1, 2006 #4
    Hey, I'm the not so bright guy saying, its all about common knowledge. Look at the triangles? Did your teacher or resource say the equation a2+b2=c2 only works for right triangles?
    In geometry, (the part of the course i practically failed) you can find right triangles in the first triangle, just by making it look like there is. When you, figured out to put a line in the middle you would need an equation.
    The x in your diagrams are defined as a variable. you need that variable to be able to plug into your equation. Then its all about putting the pieces together.
    When i had problems like these i usually refer to my notes seeing if i had any other info on triangles. At that time i didn't know cosine law and sine law, but's that's a different ball league.

    I'm not so bright and yet i practice my studies and homework to be the 80% dude.
    An hour a day keeps the teacher away (from looking at your homework)
  6. Mar 2, 2006 #5
    For right triangles the longest side is called hypotnuse, the other to sides are legs/arms. Usually most diagrams of (right) triangles have angles that correspond to the side opposite the angle. ie Angle C, the side opposite is c, and c is usually denoted as the hypotnuse which makes angle C=90 degrees.
  7. Mar 2, 2006 #6
    You can't cut it in half because 2 does not equal 4.
  8. Mar 2, 2006 #7
    hmmm, good point, but you could set up a system of equations to solve for the altitude and then solve for x.
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