# Analyze and Classify Triangles

Examples, solutions, and videos to help Grade 4 students learn how to analyze and classify triangles based on side length, angle measure or both.

Common Core Standards: 4.MD.7

### New York State Common Core Math Grade 4, Module 4, Lesson 13

NYS Math Module 4 Grade 4 Lesson 13 Application Problem

Fold Triangles A, B, and C to show their lines of symmetry. Use a straightedge to trace each fold. Discuss with your partners the relationships of symmetric shapes to angles and side lengths.

NYS Math Module 4 Grade 4 Lesson 13 Problem 2

Measure and classify triangles by side length and angle measure.

NYS Math Module 4 Grade 4 Lesson 13 Problem Set

Types of Triangles: Equilateral, Isosceles, Scalene, Acute, Right, Obtuse

1. Classify each triangle by its side lengths and angle measurements. Circle the correct names.
2. ABC has one line of symmetry as shown. What does this tell you about the measures of ∠A and ∠C ?
3. DEF has three lines of symmetry as shown.
a. How can the lines of symmetry help you figure out which angles are equal?
b. DEF has a perimeter of 30 cm. Label the side lengths.
4. Use a ruler to connect points to form 2 other triangles. Use each point only once. None of the triangles may overlap. One or two points will be unused. Name and classify the 3 triangles below.
5. a. List three points from the grid above that, when connected by segments, do not result in a triangle.
b. Why didn’t the three points you listed result in a triangle when connected by segments?
c. Can a triangle have 2 right angles? Explain.

NYS Math Module 4 Grade 4 Lesson 13 Homework

1. Classify each triangle by its side lengths and angle measurements. Circle the correct names. Use a ruler and a right angle template to prove your classifications.
2. a. ABC has one line of symmetry as shown. Is the measure of ∠A greater than, less than, or equal to ∠C?
b. DEF is scalene. What do you observe about its angles? Explain.
3. Use a ruler to connect points to form two other triangles. Use each point only once. None of the triangles may overlap. Two points will be unused. Name and classify the three triangles below.
4. If the perimeter of an equilateral triangle is 15 cm, what is the length of each side?
5. Can a triangle have more than one obtuse angle? Explain.
6. Can a triangle have one obtuse angle and one right angle? Explain.

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