Bell Ringer What does the word congruent mean? Name two things that are congruent. What is the symbol we use to denote congruence?

Geometry 4.1 Congruent Figures LEQ: How do you identify the corresponding parts of congruent figures?

Congruent Figures Two objects are congruent ( ) if they have the same size and shape. Two figures are congruent if and only if their vertices can be matched up so that corresponding parts (angles and sides) of the figures are congruent. When writing which figures are congruent, be sure to write the vertices in the same order.

A CB R ST Triangle ABCTriangle RST

A CB R ST Triangle ABCTriangle RST

A CB J KL Quadrilateral ABCDQuadrilateral JKLM DM

A CB J KL Quadrilateral ABCDQuadrilateral JKLM DM

Congruent Figures Sometimes you have to change the position of the figures to match up vertices Practice “spinning”, “sliding” and “flipping” the figures mentally

SPIN and SLIDE What would this figure look like if it had been flipped (reflected) ?

Defn. of Congruent Triangles Two triangles are congruent ( ) if and only if their vertices can be matched up so that the corresponding parts (angles and sides) of the triangles are congruent. A BC D E F

∆ ABC ∆ DEF Defn. of Congruent Triangles Two triangles are congruent ( ) if and only if their vertices can be matched up so that the corresponding parts (angles and sides) of the triangles are congruent. A BC D EF 7 A D 7 7 B E 7 7 C F 7 ABDE BCEF CAFD The order must match.

When the definition of congruent triangles is used in a proof, use the wording: CPCTC “corresponding parts of congruent triangles are congruent”

Complete the congruence statement.

Write a statement that indicates that the triangles are congruent.

Name 3 pairs of corresponding sides. Name 3 pairs of corresponding angles. Is it correct to say ? M A B N O Y

Complete the statements given.. Why is ? O C B D A

Name the coordinates of B, I, and G. Name the coordinates of a point D, such that ∆BIG  ∆DIG. Name the coordinates of a point T, such that I B G O P O 5 510

Homework P. 120 # 1-11 Don’t be shy. Draw diagrams. You will NOT be graded on your artistry.