Which three lengths can NOT be the side lengths of a triangle?
A. 2, 8, 8
B. 2, 3, 6
C. 4, 5, 7
D. 5, 6, 9
To solve this problem, you must understand a relationship about triangles: the length of two smaller legs must be greater than the longest leg. in other words,
If this condition is false, a triangle cannot exist because a side length is too long.
Let's see if A is the correct answer:
First, identify which leg is the longest. In this case, there are two legs with length 8. That is OK. Only one of them can be substituted in for Leg3.
True. This statement is true. Because this is true, that means that a triangle can have the side lengths of length 2,8, and 8.
Let's see if B is the correct answer:
False. As aforementioned, if the statement is false, then a triangle cannot exist with the given side lengths. This is the correct answer. For fun, let's try the other answer choices anyway! Let's test out C:
9>7 is a true statement, so a triangle can exist.
And finally, D:
Yes, a triangle can exist with these parameters, too. Therefore, B is the only correct answer.
Try drawing a triangle with sides 7cm, 2cm and 3cm
Make the base 7 cm long.
Actually draw this on a peice of paper and see if you can do it, or try to work out why you can't do it :)