Why is It?
I have just looked through copies of 10 current high school geometries and in not one of them can I find a direct and explicit proof of the fact that if the square on one side of a triangle equals the sum of the squares on the other 2 sides, it is a right triangle. In some books it is proved indirectly by proving its converse and its opposite, but no attention is called to the fact. Some authors use the fact in problems without having proved it or mentioned it and these same authors seem worried in their opening chapters if the converse of any little proposition is assumed to be true without giving the proof of it.
1973 ◽
Vol 16
(2)
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pp. 257-266
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2021 ◽
Vol 8
(12)
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pp. 374-377
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2015 ◽
Vol 42
(suppl 1)
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pp. 31-33
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2021 ◽
Vol 2
(1)
◽
pp. 30-39
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2021 ◽
Vol 04
(12)
◽
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