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Jodi
Member since Aug1203

Aug1103, 11:48 PM (EST) 

"Pythagoras theory"

Hi there I just dropped by to ask if you can tell me please: Can you use Pythagoras theory to create a triangle with a perfect right angle? ie I want to measure ab at say, 2 metres, then bc at say 3 metres, then for instance find the distance ac to create a perfect right angle. You help's much appreciated Jodi 

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Vladimir
Member since Jun2203

Aug1203, 09:11 AM (EST) 

2. "RE: Pythagoras theory"
In response to message #0

For practical applications, AB = 2m and BC = 3m would be inconvenient, for CA = Ö(4 + 9) = Ö13m. But you can easily generate plenty of integer Pythagorean triples such that a^{2} + b^{2} = c^{2}. Certain Pythagorean triples were used in ancient times in construction work long before Pythagoras discovered his theorem. For example, the ancient Egyptians knew the Pythagorean triple (3, 4, 5) and the ancient Indians (from India) the Pythagorean triple (5, 12, 13). I imagine that they made a circular rope with 3 + 4 + 5 = 12 resp. or 5 + 12 + 13 = 30 equidistant marks labeled 1, 2, ..., 12 resp. 30 and then they stretched the rope at the marks 3, 7, and 12 resp. 5, 17, and 30. 

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Graham C
Member since Feb503

Aug1903, 11:24 PM (EST) 

3. "RE: Pythagoras theory"
In response to message #0

This reminds me of an old problem (I'm thinking 40 years ago) which some people may not be familiar with. You have an inexhaustible supply of matches, which can be linked together at their ends, but not rigidly  i.e. they can wiggle around. Your task is to construct a rigid rightangle that cannot be deformed (other than by breaking the matches). What is the minimum number of matches you need? 

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