Caitlin Bryant

Learning Triangle Congruence Postulates using TRI-FID

What is the difference between postulate and theorem?

Postulate- something we assume to be true without proof.

Theorem- something that can be proven based on postulates.

Review of Triangle Postulates:

Side-Angle-Side (SAS)

If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent.

Side-Side-Side (SSS)

If all three sides on one triangle are congruent to corresponding sides on another triangle, the triangles are congruent.

Angle-Side-Angle (ASA)

If two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the triangles are congruent.

Angle-Angle-Side (AAS)

If two angles and the non-included side of one triangle are congruent to two angles and the non-included side of another triangle, the two triangles are congruent.

Here’s how it works…There are 2 worksheets. On one worksheet

is 8 triangles. The second worksheet has numerous triangles where some are congruent to the triangles on the first sheet. The object is to match one from the first to the second using the 4 Triangle Postulates.

For example:Worksheet 1: Worksheet

2:A

B

C

3 1

1S-

S-S

Once you’ve matched each triangle to the one that it is congruent to, use the numbers from the triangle and apply them to the TRI-FID.

For Example:This triangle has the numbers 1-1-3 and are read in

this order.On the TRI-FID grid, this corresponds to the letter

G.Once you’ve found the corresponding letter, put it

in the space provided for the correct question #:_G_ ___ and so on…

1. 2.3 1

1

TRI-FID Grid: