<PRE><B>Question 1026243</B>
Gaining a solid intuitive understanding about this theorem will enable you to think through the question and answer it.


Try taking any two lengths, known lengths if you wish; and you know you need ONE MORE length if you want to form a triangle.  Try as example, lengths 7 and 10.  Can the next length to choose be  7+10=17 and allow formation of a triangle?  



.....NO!


Why? 



Try choosing a smaller length instead.
Can you choose length of 16 and form a triangle?
Should be YES.


Now, instead of choosing 17 or 16, try choosing 18.
Can you form a triangle using lengths 7, 10, and 18?

...


.... NO!

Why?



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Now, can you go back to your given three sides of 4, 5, and 9, and determine if these can form a triangle?</PRE>