# Lesson 2 Ways to Look at Triangles

• Let’s sort and analyze triangles.

## Warm-up Number Talk: Sums and Products

Find the value of each expression mentally.

## Problem 1

From the set of triangle cards, find all the triangles that have each attribute. Record their letter names here.

 No right angles Parallel sides Perpendicular sides The same length for all sides The same size for all angles More than one right angle More than one obtuse angle More than one acute angle Foldable into two equal halves

## Problem 2

Choose one sentence to complete based on your work.

1. I noticed that some triangles  …

2. I noticed that all triangles  …

3. I noticed that no triangles  …

## Activity 2 The Right Kind of Triangle

1. Identify all shapes that are right triangles. For each right triangle, mark the right angle with a small square.

2. Explain why the other shapes are not right triangles.

## Problem 1

1. Which of the triangles are right triangles?

2. Which of the triangles have an obtuse angle?

3. Which of the triangles have 3 acute angles?