1. Mr. Schaab’s Geometry Class Our Lady of Providence Jr.-Sr. High School 2014-2015

2.  Right Triangle – A triangle that contains one right angle.  Hypotenuse – The side of a right triangle opposite the right angle. The hypotenuse is always the longest side of the triangle.  Leg – A side adjacent to the right angle of a right triangle.

3.  The Hypotenuse-Leg Congruence Theorem:  If the hypotenuse and one leg of a right triangle are congruent to the hypotenuse and a leg of a second right triangle, then the two triangles are congruent. ▲ABC ≅ ▲DEF▲WHT ≅ ▲WST

4.  CPCTC – Corresponding Parts of Congruent Triangles are Congruent.  After two triangles have been proven congruent using one of our 5 theorems, you can use CPCTC to prove that other corresponding parts of those two triangles are also congruent. Example: Explain how you could prove that ∠ N ≅ ∠ P. The triangles are congruent by SSS, and ∠ N corresponds to ∠ P, so by CPCTC the two angles must be congruent.

5.  Important: unlike the first 5 theorems we learned to use on triangle proofs, CPCTC is never used to prove that two triangles are congruent.  CPCTC can only be used to prove that corresponding parts are congruent after you have proven that two triangles are congruent using SSS, SAS, ASA, AAS, or HL.  If a proof asks you to prove that two corresponding parts of triangles are congruent, chances are you’ll use CPCTC as your final step.