Lessons for G.SRT.B.5
AA similarityTwo pairs of congruent angles are enough to make two triangles similar.Lesson
SSS, SAS, ASA, AASThe short lists of matching parts that force two triangles to be congruent.Lesson
Hypotenuse leg congruenceRight triangles are congruent when their hypotenuses match and one pair of legs matches.Lesson
Planning a congruence proofMarking the figure, listing what is given, and choosing which criterion those given parts can reach.Lesson
Proving parts congruent after the trianglesProving two triangles congruent first so that a matching side or angle can then be claimed.Lesson
Proofs about similar figuresArguments that establish proportional sides once two pairs of angles have been matched.Lesson
Proving two triangles similarFinding two congruent pairs of angles, often from parallel lines or from a shared angle.Lesson
SSS and SAS similarityTriangles are similar when all three pairs of sides are in the same ratio, or when two pairs are and the angles between them are equal.Lesson
Why AAA and SSA failTwo sides and an angle that is not between them can build two different triangles, so they do not force congruence.Lesson
Printable Worksheets
AA similarity worksheet (PDF)Printable worksheet with answer keyPreview
SSS, SAS, ASA, AAS worksheet (PDF)Printable worksheet with answer keyPreview
Hypotenuse leg congruence worksheet (PDF)Printable worksheet with answer keyPreview
Planning a congruence proof worksheet (PDF)Printable worksheet with answer keyPreview
Proving parts congruent after the triangles worksheet (PDF)Printable worksheet with answer keyPreview
Proving two triangles similar worksheet (PDF)Printable worksheet with answer keyPreview
SSS and SAS similarity worksheet (PDF)Printable worksheet with answer keyPreview
Why AAA and SSA fail worksheet (PDF)Printable worksheet with answer keyPreview