athomeontheprairie Posted January 6, 2016 Share Posted January 6, 2016 Can someone offer me an explanation? Or confirm that I'm not crazy. I'm good with either. "The Sum of any two sides (of a triangle) must be greater than the third side" Examples given: 3, 4, 5 4, 5, 8 4, 6, 9 In the teacher's manual there is one set of numbers marked as not a triangle, though it meets the above rule. Why? The set is: 15, 6, 12 Why is this not a triangle? 15 is less than 18 (6+12) 6 is less than 27 (15+12) 12 is less than 21 (15+6) It meets the rules. Why is it not a triangle? (Or maybe the TM is wrong, but it isn't listed as a known correction on the company website.) Quote Link to comment Share on other sites More sharing options...
regentrude Posted January 6, 2016 Share Posted January 6, 2016 (edited) It is a mistake in the TM. Of course it is perfectly possible to have a triangle with side lengths 15, 6, and 12. I just drew one. Edited January 6, 2016 by regentrude 4 Quote Link to comment Share on other sites More sharing options...
MorningGlory Posted January 6, 2016 Share Posted January 6, 2016 You are not crazy! :-) http://www.mathwarehouse.com/triangle-calculator/online.php?sa=15&sb=6&sc=12#triangleAppData 2 Quote Link to comment Share on other sites More sharing options...
raptor_dad Posted January 6, 2016 Share Posted January 6, 2016 Typo... it is supposed to be 5, 6, 12. Which obviously isn't a triangle. 2 Quote Link to comment Share on other sites More sharing options...
athomeontheprairie Posted January 6, 2016 Author Share Posted January 6, 2016 Typo... it is supposed to be 5, 6, 12. Which obviously isn't a triangle. This is likely. Thanks! Quote Link to comment Share on other sites More sharing options...
athomeontheprairie Posted January 6, 2016 Author Share Posted January 6, 2016 I just drew one.So did I ☺ Quote Link to comment Share on other sites More sharing options...
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