Lesson 6-4

Example 1 Identify Congruent Polygons
Determine whether the triangles shown are congruent.
If so, name the corresponding parts and write a 
congruence statement.

The arcs indicate that A  D, B  E, and C  F.

The side measures indicate that .

Since all pairs of corresponding angles and sides are congruent, the two triangles are congruent. One congruence statement is ABC  DEF.

Example 2 Find Missing Measures
In the figure, XYZ  TRI. Find mT.		

According to the congruence statement, 
X and T are corresponding angles. 

So, X  T. Since mX = 50, mT = 50.

Example 3 Find Missing Measures  
Refer to the figure in Example 2 above. Find TR.

corresponds to. So,  . Since XY = 12 centimeters, TR = 12 centimeters.