# Lesson 8 Sort Triangles

Let’s sort triangles.

## Warm-up Estimation Exploration: Angle Measure

What is the measure of the angle?

Record an estimate that is:

too low | about right | too high |
---|---|---|

## Activity 1 The Right Fit

Find a triangle card that fits in each space on the grid.

If you don’t think it is possible to find a triangle that fits certain criteria, explain why not.

all three side lengths are different | exactly two of the side lengths are the same | all three side lengths are the same | |
---|---|---|---|

has a 90 degree angle | |||

has an angle that is greater than 90 degrees | |||

all three angles are less than 90 degrees |

Explanations:

## Activity 2 All, Some, None

## Problem 1

Sort the triangle cards from the previous activity in a way that makes sense to you. Describe how you sorted the cards.

## Problem 2

Now sort out the triangles with a 90 degree angle. For these triangles, write statements about each category.

All of the triangles with a 90 degree angle …

Some of the triangles with a 90 degree angle …

None of the triangles with a 90 degree angle …

## Practice Problem

## Problem 1

For each description, draw a **right** triangle with the described side lengths on the grid or explain why there is no such right triangle.

2 equal side lengths

3 equal side lengths

3 different side lengths