Curated OER
What is a Rectangle?
What are the characteristics and properties of a quadrilateral that make it a rectangle? Four sides? Right angles? Parallel sides? Watch this video and follow along as the instructor explains the terms and properties that make a...
Curated OER
What is a Quadrilateral?
What's so special about quadrilaterals? There are five special types, yes, five. Can you name them? The instructor in this video diagrams and illustrates the special types of quadrilaterals and explains what makes each one special.
Curated OER
What is a Parallelogram?
A rectangle, a rhombus, a square, a trapezoid - are any of these a parallelogram? What are the criteria that make a shape a parallelogram? It has something to do with parallel sides, congruent sides, and congruent angles. Help your young...
Curated OER
How Do You Identify Corresponding Parts in Congruent Triangles?
Congruent, corresponding, congruent corresponding. If two figures are congruent, then their corresponding sides and corresponding angles are congruent. Is this to be believed? Watch this video and see if the proof is in the pudding.
Curated OER
What is a Transversal?
There are two parallel lines intersected by one straight line, what's that one line called? A transversal. There are a few more things to know about transversal lines and the angles they create. What are vertical angles? Are they...
Curated OER
How Do You Find Missing Angles in an Isosceles Triangle?
Finding the missing values of two angles in an isosceles triangle is not as difficult as it sounds. But how can two out of three angle's measurements be found? Well, there are special properties about an isosceles triangle which make...
Curated OER
How Do You Find Missing Measurements of Similar Figures Using a Proportion?
Two similar triangles have the same angles, but their legs have different lengths. This means their angles are congruent, and thusly, their corresponding sides are congruent. So there is a missing measurement that needs to be found. Set...
Curated OER
How Do You Classify Quadrilaterals?
A rectangle, a rhombus, a square, a trapezoid, and a parallelogram, are these quadrilaterals? What are the criteria that make and shape a quadrilateral? It has something to do with parallel sides, congruent sides, and congruent angles....
Virtual Nerd
What is the Triangle Sum Theorem?
If you add the value of the three interior angles in a triangle will it equal 180 degrees? Yes it will. The instructor illustrates and proves the Triangle Sum Theorem. Follow closely as she explains her proof.
Loyola University Chicago
Math Flix: Congruency
This QuickTime movie provides an opportunity to learn about the basic geometric term congruency. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept.
Sophia Learning
Sophia: Cpctc: Lesson 1
This lesson [8:19] will demonstrate the use of CPCTC in triangle congruency proofs. It is 1 of 4 in the series titled "CPCTC."
Virtual Nerd
Virtual Nerd: Construct Equilateral Triangle and Square Inscribed in a Circle
Two videos on geometric constructions. One explains how to construct an equilateral triangle using a ruler and compass. The second describes how to draw a square using a compass and a straightedge.
Sophia Learning
Sophia: Reflexive Property of Congruence and Equality: Lesson 1
This lesson will introduce the reflexive property of congruence, and the reflexive property of equality. It is 1 of 6 in the series titled "Reflexive Property of Congruence and Equality."
Virtual Nerd
Virtual Nerd: What Does Congruent Mean?
Video tutorial explores the term congruent which is often used to describe figures that have the same size and shape. [5:21]
Khan Academy
Khan Academy: Triangles: Finding Area Using Similarity and Congruence
Explains how to determine the area of a pentagonal shaded region in a triangle. The triangle that is broken into multiple similar and congruent triangles.
Sophia Learning
Sophia: Congruence Statement
This video tutorial demonstrates how to use a congruence statement to prove to objects congruent. A short quiz accompanies the lesson. [1:09]
Khan Academy
Khan Academy: Geometry: Proof: Opposite Sides of Parallelogram Congruent
Demonstrates how to prove that the opposite sides of a parallelogram are congruent based on knowledge of the special angles created when parallel lines are cut by a transversal and the triangle congruency postulates. [8:30]
Khan Academy
Khan Academy: Congruence and Similarity Harder Example
This video lesson from Khan Academy covers congruence and similarity for eighth grade mathematics students. Watch Sal work through a harder congruence and similarity problem.
Khan Academy
Khan Academy: Congruence and Similarity Basic Example
This video lesson from Khan Academy covers congruence and similarity for eighth-grade mathematics students. Watch Sal work through a basic congruence and similarity problem.
Sophia Learning
Sophia: Corresponding Angles Converse: Lesson 6
This lesson [5:22] will demonstrate how to prove lines parallel with the converse of the corresponding angles postulate. It is 6 of 6 in the series titled "Corresponding Angles Converse."
Sophia Learning
Sophia: Corresponding Angles Converse: Lesson 1
This lesson will demonstrate how to prove lines parallel with the converse of the corresponding angles postulate. It is 1 of 6 in the series titled "Corresponding Angles Converse." [2:37]
Sophia Learning
Sophia: Corresponding Parts: Lesson 1
This lesson [2:00] will define the phrase corresponding parts (e.g. angles, sides, etc.). It is 1 of 5 in the series titled "Corresponding Parts."
Sophia Learning
Sophia: Using Similar Triangles to Make Indirect Measurements
This lesson explains why similar triangles can be used to make indirect measurements, and provides an example.
Sophia Learning
Sophia: Making Arguments Using the Properties of Equality and Congruence
This lesson will demonstrate how to apply the different properties of equality and congruence to make geometric logical arguments.