Geometry 4 1 Congruent Figures Congruent Figures Two

Geometry 4. 1 Congruent Figures

Congruent Figures • Two objects are congruent ( the same size and shape ) if they have • 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 R B C Triangle ABC S T Triangle RST

A R B C Triangle ABC S T Triangle RST

D A B M J C Quadrilateral ABCD K L Quadrilateral JKLM

D A B M J C Quadrilateral ABCD K L Quadrilateral JKLM

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

SPIN and SLIDE

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 E D B C F

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. ∆ ABC ∆ DEF 7 F C E 7 C B D 7 A A 7 The order must match. F AB DE BC EF CA FD

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

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

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

B I T Name the coordinates of B, I, and G. Name the coordinates of a point D, such that. Name the coordinates of a point O, such that G . P

Homework • pg. 120 #1 -6, 10 -13, (15 -21 odd) • Makeups next week are Wednesday after school • Graphing Calculator?