G.2.4 Lesson Summary
This activity is the first introduction to the criteria we need to show that 2 triangles are congruent. We are going to spend the next few weeks focusing on these ideas. No need to have this mastered today - just the idea that we can use 3 pieces of specific information to show 2 triangles are congruent.
Triangle Congruence Criteria Assertions:
Our experiements today lead us to believe that these combinations of sides and angles will show 2 triangles are congruent:
• Angle-Side-Angle (ASA) “Two angles and the included side.”
• Angle-Angle-Side (AAS) “Two angles and the non included side.”
• Side-Angle-Side (SAS) “Two sides and the included angle.”
• Side-Side-Side (SSS) “All three sides.”
• Hyptenuse-Leg (HL) "The hypotenuse and leg of a right triangle (so also a 90 degree angle)."
Sets of information that are not valid triangle congruence criteria
Our experiments today showed us that these combinations of sides and angles will NOT show 2 triangles are congruent:
• Side
• Side-Angle
• Side-Side-Angle (SSA) "Two sides and a non-included angle"
(the easy way to remember this one is that it can make a bad word when the A is not between the 2 S's,
but we choose to not write it in that order to be polite!)
• Angle-Angle (AA) This one makes similar triangles!