Unit 6, Lesson 9# Conditions for Unique Triangle―Three Sides Two Sides and Included Angle

EngageNY 45 min(s)

Students understand that two triangles are identical if all corresponding sides are equal under some correspondence; three side lengths of a triangle determine a unique triangle. Students understand that two triangles are identical if two corresponding sides and the included angle are equal under some correspondence; two sides and an included angle of a triangle determine a unique triangle. Students finished Lesson 8 with the driving question: What conditions produce identical triangles? More specifically, given a few measurements of the sides and angles of a known triangle, but not necessarily given the relationship of those sides and angles, is it possible to produce a triangle identical to the original triangle?