1. Lesson 4-7 Congruence Transformations
TARGETS
ID reflections, translations, and rotations.
Verify congruence after congruence transformation.
Targets

2. Types of transformations
LESSON 4-7: Congruence Transformations
Translation or “slide”
moves all the pts the
same distance & in the
same direction
Preimage: original figure
Reflection or “flip” over
a line called the line of
reflection
Rotation or “turn” around
a fixed point called the
center of rotation
Types of transformations

3. LESSON 4-7: Congruence Transformations
EXAMPLE 1 & 2
Identify Congruence Transformations
Identify the type of congruence transformation shown as a reflection, translation, or rotation.
reflection
translation
translation
rotation
translation
reflection
rotation
reflection
Example 1 & 2

4. LESSON 4-7: Congruence Transformations
EXAMPLE 1 & 2
Verify Congruence after a Transformation
Triangle PQR with vertices P(4, 2), Q(3, –3), and R(5, –2) is a transformation of ΔJKL with vertices J(–2, 0), K(–3, –5), and L(–1, –4). Graph the original figure and its image. Identify the transformation and verify that it is a congruence transformation.
Example 3

5. LESSON 4-7: Congruence Transformations
EXAMPLE 1 & 2
Verify Congruence after a Transformation
Triangle PQR with vertices P(4, 2), Q(3, –3), and R(5, –2) is a transformation of ΔJKL with vertices J(–2, 0), K(–3, –5), and L(–1, –4). Graph the original figure and its image. Identify the transformation and verify that it is a congruence transformation.
Example 3

6. Verify Congruence after a Transformation
Solve Graph each figure. The transformation appears to be a translation 6 units right and 2 units up. Find the measures of the sides of each triangle.
Example 3

7. Verify Congruence after a Transformation
Example 3

8. Answer: By SSS, ΔJKL  ΔPQR.
Verify Congruence after a Transformation
Answer: By SSS, ΔJKL  ΔPQR.
Check Use the definition of a translation. Use a ruler to measure and compare each side of the triangles. The sides are congruent, so the triangles are congruent.
Example 3

9. 4-7 Word Problem Practice
LESSON 4-7 & 4-8: Geometric Transformations
Homework
Pg #7-16, 19, 20
&
4-7 Word Problem Practice
Homework