Can 2, 11 and 9 make a triangle

Step by step

The question

Question: can sides of 2, 11 and 9 make a triangle?

For a triangle, the two short sides together must be longer than the longest side.

Else they cannot meet.

1 Add the two short sides

The longest side is 11.

We lay it down first.

The two short sides are 2 and 9.

Together: 11.

2 Compare with the longest

Swing them up from the ends.

11 is exactly 11: they only meet lying flat on the long side.

Careful!

2 plus 9 is exactly 11.

The sides lie flat on top of each other.

That is a line, not a triangle.

So no: they cannot make a triangle.

3 Check

Let's check the other two pairs: 2 plus 11 is 13, and 9 plus 11 is 20.

Both are more than the third side.

So only the short pair decides.

So the answer is right!

Let's look back.

First: add the two short sides.

Then: compare with the longest.

Last: check.