Mark all the groups of lengths that could be the side lengths of a triangle? a. 18 inches, 6 inches, 13 inches b. 4 inches, 6 inches, 8 inches c. 6 inches , 18 inches, 12 inches d. 8 inches, 16 inches, 10 inches

Since the rule of the triangle's sides states that two sides of a triangle's sum must be greater than the third side.

Ex.

if the sides are x, y, z

x+y>z
x+z>y
y+z>x

Thus we can apply this to this problem.

A.
18+6 >13
18+13>6   These all work. 
13+6>18

B.
4+6>8
4+8>6 These all work as well.
4+6>8

C.
6+18>12
6+12>18 We know right away that this will not work as 6+12 = 18.

D.
8+16>10
8+10>16 This works too.
10+16>8

Your answer should be A, B, D. Hope this helps!

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