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Can 4, 6, 10 make a triangle

Step by step, with the reason for every step · Can it make a triangle · Geometry

Step by step

The question

Question: can sides of 4, 6 and 10 make a triangle?

sides 4, 6, 10

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

Else they cannot meet.

the two short sides must reach
round the longest one

1 Add the two short sides

The longest side is 10.

We lay it down first.

The two short sides are 4 and 6.

Together: 10.

= 4 + 6 = 10

2 Compare with the longest

Swing them up from the ends.

10 is exactly 10: they only meet lying flat on the long side.

Careful!

4 plus 6 is exactly 10.

The sides lie flat on top of each other.

That is a line, not a triangle.

Careful: equal is not enough: it lies flat

So no: they cannot make a triangle.

= 10 = 10 → no triangle

3 Check

Let's check the other two pairs: 4 plus 10 is 14, and 6 plus 10 is 16.

Both are more than the third side.

So only the short pair decides.

So the answer is right!

4 + 10 = 14 > 6, 6 + 10 = 16 > 4

Let's look back.

First: add the two short sides.

Then: compare with the longest.

Last: check.

Answer
= 10 = 10 → no triangle

Your turn

Try this one yourself, then check:

sides 8, 9, 17
Show the answer
no

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