Question 195490: Hi I have a question about how to find out if a set of three numbers can be sides of a triangle or not. I remember doing this in class, & I remember that it was really easy... I think it's something like if you get a certain number from using the Pythagorean Theorem, it's a right triangle, if you get this number, it's an acute, etc.... I just don't remember what exactly to do, although I do recall that it involves the Pythagorean Theorem, correct? I don't have the notes from this b/c I cleared out my binder. It gets too full if I keep all of the papers from the entire year, so I take old chapters out. No, I don't know any Pythagorean triplets, & no i don't think the units matter. This is all I remember.... This is the question:
Which of the following could not be the lengths of the sides of a triangle?
A: 5km, 2km, 4km
B: 3cm, 4cm, 5cm <== might be a triplet...
C:4in, 6in, 8in
D:6ft, 3ft, 9ft
Thank you in advance, I'd love your help! :D
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Which of the following could not be the lengths of the sides of a triangle?
A: 5km, 2km, 4km
B: 3cm, 4cm, 5cm <== might be a triplet...
C:4in, 6in, 8in
D:6ft, 3ft, 9ft
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This is not a Pythagorean problem.
You are not checking to see if you have a right triangle.
You want to know if the three sides could be the sides of a triangle (any
triangle).
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Criteria: The sum of every two sides must be greater than the 3rd side.
Example: sides of 1,2, and 7 could not be a triangle.
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Your Problem.
6,3,9 would not form a triangle.
Try it and you'll see.
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Cheers,
Stan H.
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