Using HL

When you have a right triangle, consider the Hypotenuse-Leg Theorem.  This video link gives a good example for the last postulate/theorem that we use to prove triangles congruent.  The example shows another way to do proofs - by using flow-chart style proofs.

But, if you prefer the traditional two-colume proof, this video is for you!

Isosceles Triangles

This is a good review of what we learned just prior to the break.  Watch this video to review some of the key concepts in isosceles triangles.  The example that follows is also a challenging practice.

Using AAS

This video link demonstrates the features of the Angle-Angle-Side Theorem.  Of course, there's an example that follows.

Using SSS

One of the easiest postulates to use is the Side-Side-Side Postulate.  This video link gives us a quick overview of what we learned.

Using SAS

Very similar in concept to the ASA Postulate, here is a video link to the description of the Side-Angle-Side Postulate.  Be sure to understand the difference between SAS and ASA.

Using ASA

Here is a video link to the description of Angle-Side-Angle Postulate along with an example.

Proving Congruent Triangles

The image above sets the beginning stages of this proof.  Try to use our class examples to complete the proof before watching this video.

Exterior Angles

Try the problem that follows the initial instruction of triangle exterior angles.  This skill will help us solve many interesting problems in the upcoming section.

The Louvre Museum

The Lourve Museum is a destination of many Paris tourists.  Check out its interactive website.  The entrance to the museum is a giant glass pyramid made of many triangles.

Pyramids

Slant faces of pyramids are triangular. We'll learn more about 3-D figures in the spring! Can't you find other triangular objects in everyday life?

Triangle Sum Theorem

The sum of the three angles in any triangle is 180 degrees.  Any triangle!  They always add up to 180.  Can it be any easier?  = )

Check out this video!  Try the problem at the bottom of the slide.  Post your answer for x, y, and z in the comments section below.  Thanks!