The fourth step in Cornelius' proof is incorrect. Pythagorean theorem is a^2 + b^2 = c^2 where c is the hypotenuse, as he had it. His fourth step, where he divided by 2, is not needed. the 4th part of the proof should be 25 = c^2. When you take the square root of both sides, you will then find C. Dividing by 2 does not cancel out squares. Dan bru was correct though failing to give a proof. I would have to say that I like think the best "think outside of the box" answer by far is the answer that was given by the student who was taking this test.
7 comments:
Glad to have you back. So glad to hear that things are better, which I hope means, fine.
x = 5
Pythagorean theorem
a^2 + b^2 = c^2
4^2 + 3^2 = c^2
16 + 9 = 25
25/2 = c^2/2
12.5
square root of 25 = 5 my bad
The fourth step in Cornelius' proof is incorrect. Pythagorean theorem is a^2 + b^2 = c^2 where c is the hypotenuse, as he had it. His fourth step, where he divided by 2, is not needed. the 4th part of the proof should be 25 = c^2. When you take the square root of both sides, you will then find C. Dividing by 2 does not cancel out squares. Dan bru was correct though failing to give a proof. I would have to say that I like think the best "think outside of the box" answer by far is the answer that was given by the student who was taking this test.
5
wow. I should run a blog of geometry puzzels. *THAT* would get the comments flowing. :-)
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