In this congruent triangles worksheet, high schoolers solve four multiple choice problems. Students determine which statement is the appropriate reasoning to say that two triangles are congruent.

Students explore the concept of congruent triangles.  In this congruent triangles lesson, students use Cabri Jr. to construct two congruent triangles using circles.  Students determine if the two triangles are congruent by...

While it may seem incredibly obvious to the geometry student that congruent sides make congruent triangles, the proving of this by definition actually takes a bit of work. This exercise steps the class through this kind of proof by...

Triangles are all about threes, and practicing proving postulates is a great way to get started. The first page of the worksheet provides a brief introduction of the different properties and postulates. The remaining pages contain...

Combine transformations and triangle congruence in a single lesson. Scholars learn to view congruent triangles as a rigid transformation. Using triangle congruence criteria, learners identify congruent triangles and the rigid...

Creating a triangles is as easy as 5, 6, 7. Using a ruler and compass to measure off lengths, a short video shows how to construct a triangle with three specific side lengths. The example creates a triangle with side lengths of 5 cm, 6...

The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...

Looking for a different approach to triangle congruence criteria? Employ transformations to determine congruent triangles. Learners list the transformations required to map one triangle to the next. They learn to identify congruence...

In this congruent triangles worksheet, 10th graders solve and complete 16 different types of problems. First, they name the corresponding parts of the congruent triangles shown and draw a picture. Then, students list the five ways to...

How do you know if a pair of triangles are congruent? Use the lesson to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through transformations and...

How can you prove it? Guide classes through an exploration of two possible triangle congruence criteria: AAS and HL. Learners connect this criteria to those previous learned and also explore criteria that does not work. The lesson plan...

Learn about constructing figures, proofs, and transformations. The seventh unit in a course of nine makes the connections between geometric constructions, congruence, and proofs. Scholars learn to construct special quadrilaterals,...

High schoolers identify properties of triangles. In this geometry lesson plan, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.

Students discover three lettered postulates that prove triangles congruent.

Construct yourself a winning geometry unit. A set of lessons introduces geometry scholars to constructions and proofs with compasses and straightedges. It also covers triangle congruence through transformations. This is the second of...

Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...

Tenth graders explore congruent triangles.  In this geometry lesson, 10th graders investigate the conditions necessary to prove two triangles are congruent by SSS, ASA, AAS, or SAS. 

Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...

In this congruent triangles worksheet, 10th graders solve 5 various types of geometry problems related to triangles. First, they draw and label triangles, indicating the additional pairs of corresponding parts that would have to be...

In this triangle congruence worksheet, students review 4 triangle congruence properties and 4 examples. Students are then prompted to complete 15 problems analyzing whether two triangles are congruent and determine by which property.

Students discover that the sum of the lengths of any two sides of a triangle must be greater than the third side. They are shown how a triangle is formed using three strips such as that the triangle is seen inside the strips.

In this triangle similarity worksheet, 10th graders solve and complete 12 different problems that include defining similar and 3 similar statements using only sides and angles. First, they determine if each pair of triangles shown are...

Scholars first investigate relationships in the side lengths of 30°-60°-90° triangles and 45°-45°-90° triangles. This knowledge then helps them solve problems later in the lesson about special right triangles.

Students will determine if triangles are congruent and state the appropriate congruence theorem. In this geometry lesson, students will determine what information is needed to determine if a pair of triangles are congruent using ASA,...