Answer:
Step-by-step explanation:
The triangle inequality theorem states that the sum of any two sides of a triangle os greater than the third side.
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First triangle:
Let a,b and c be the sides of the triangle:
● a = 10
● b = 20
● c = 30
Now let's apply the theorem.
● a+b = 10+20=30
That's equal to the third side (c=30)
●b+c = 50
That's greater than a.
● a+c = 40
That's greater than b.
These aren't the sides of a triangel since the first inequality isn't verified.
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Second triangle:
● a = 122
● b = 257
● c = 137
Let's apply the theorem.
● a+b = 379
That's greater than c
● a+c = 259
That's greater than b
● b+c = 394
That's greater than a
So 122,257 and 137 can be sides of a triangle.
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The third triangle:
● a = 8.6
● b = 12.2
● c = 2.7
Let's apply the theorem:
● a+b = 20.8
That's greater than c
● b+c = 14.9
That's greater than a
● a+c = 11.3
That isn't greater than b
So theses sides aren't the sides of triangle.
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● a = 1/2
● b = 1/5
● c = 1/6
Let's apply the theorem.
● a+b = 7/10
That's greater than c
● a+c = 2/3
That's greater than b
● b+c = 11/30
That isn't greater than a
So these can't be the sides of a triangle.