# Which Lengths make a Triangle? (1.2)

- Author:
- Roger Gemberling

**Move**

**the point on the slider**to change the length of the third side.

**Move the green points**(B and C) until you are able to place both points labeled C on top of each other. If both points labeled C are on top of each other, the three lengths make a triangle.

## Question 1

You are asked to make a triangle with lengths of 5, 12, and 15. Is it possible?
*Two of the three lengths are already given. So move the point on the slider to 15, then try to complete the triangle by placing one point C exactly on top of the other point C.*

## Question 2

You are asked to make a triangle with lengths of 5, 12, and 8. Is it possible?

## Question 3

You are asked to make a triangle with lengths of 5, 12, and 6. Is it possible?

## Question 4

You are asked to make a triangle with lengths of 5, 12, and 11. Is it possible? *.*

## Question 5

You are asked to make a triangle with lengths of 5, 12, and 18. Is it possible?

**shortest to longest**. Also enter the sum of sides 1 and 2 into your spreadsheet. Move the

**green points**so they are exactly on top of each other. Then place either "Y" or "N" to indicate if a triangle is possible for the given lengths. Click on

**Next Problem**to explore other combinations. Create a table with 12 examples. Make sure you have examples of both situations (work or don't work).

## Question 6

For each set of lengths that make a triangle. how does the sum of **side1 + side 2** compare to the length of** side 3**?

## Complete this Conjecture

If you are given three lengths in order from **shortest to longest**, you will have a triangle when ...