﻿ Equilateral And Isosceles Triangle Worksheets
These activity sheets will teach your students the differences between equilateral, isosceles, and scalene triangles.

Triangles are often classified by either their number of sides or the measures of their angles. If all the lengths of their sides are different it is scalene. If the length of two sides of the triangle are equal it is called isosceles. If two sides of a triangle are congruent that are considered the same in all respects. The Isosceles Triangle Theorem tells us that if you have an isosceles triangle the angles opposite the congruent sides are also congruent. If all sides are equal it is called equilateral. When it comes to angles of triangles: acute (all angles are acute), right (one right angle), obtuse (one obtuse angle), and equiangulars (you guessed it; have all equal angles).

What Are Equilateral and Isosceles Triangles? Isosceles - Suppose two sides of a triangle are congruent, the angles that are opposite are congruent. The congruent sides are called legs from the vertex angle, and the other two are base angles. These isosceles shapes are used in regular polygon areas plus, the triangles are called 45-45-90. You can find the other two isosceles triangles if you have one interior angle. The examples of the isosceles are the golden triangle, isosceles right triangles, and the faces of bipyramids as well as certain Catalan solids. Equilateral - This is a triangle that has all three sides equal or of the same length. The Equilateral has a property with all three interior angles. It is a specific case of a regular polygon, but here, with three sides. You may construct an equilateral triangle of a provided side length using a straightedge and a compass. The radius of an equilateral is half the radius of a circumcircle. All three angles are always 60 degrees. These worksheets explain how to identify these types of triangles. Students will calculate angles and side lengths of each triangle, match definitions containing angle degrees, and more.

Print Equilateral And Isosceles Triangle Worksheets

Full Lesson

This worksheet explains how to draw an isosceles triangle. A sample problem is solved.

Lesson and Practice Worksheet

This worksheets explains how to draw an equilateral triangle. A sample problem is solved, and two practice problems are provided.

More Practice Worksheet

Given triangles, students will guess and then measure the angles. Ten problems are provided.

Class Practice

Students will match the descriptions of angles and sides of each triangle. Ten problems are provided.

Class Drills and Sheets

Students will guess and then measure the angles of isosceles and equilateral triangles. Eight problems are provided.

Full Warm Up

Students will draw isosceles and equilateral triangles. Three problems are provided.

Classifying Triangles Lesson

This worksheet explains how to classify triangles. A sample problem is solved.

Lesson and Practice

If all of the angles of a triangle are less than 90 degrees, it is called an acute angled triangle. If one of the angles of a triangle is greater than 90 degrees but less than 180 degrees, it is obtuse angled triangle. And if one of the angles of a triangle is 90 degrees, it is a right angled triangle.

Worksheet

Given a description, students will classify these shapes based on the number of sides it has. Ten problems are provided.

Classifying Triangles Practice

Use all the information that is provided for you to classify triangles that are given. Ten problems are provided.

Skill Drill

Students will classify the triangles according to the measure of their sides and angles. Eight problems are provided.

Skill Warm Up

Students will classify the given triangles. Three problems are provided.

Isosceles Triangle Theorems: Lesson

Solve the problem: In Triangle MSB, < M:< S:< B is 2:1:4 is this triangle is isosceles triangle?

Worksheet 1

Show whether this triangle is a certain type of classification.

Worksheet 2

If two sides of a triangle are congruent, the angles opposite them are congruent. (True or False)

Review Worksheet

In triangle CDE, the vertices have coordinates C (0,0), D (1,1), E (-1,-1). Show whether this triangle is isosceles or not isosceles.

Quiz

Ten problems to see if you understand these concepts.

Do Now

Complete the problems. Put your answer in the "My Answer" box.