Section 4.2 Congruence and Triangles
Two figures are congruent if they have exactly the same size and shape.
Congruent Triangles Triangles that have Corresponding angles congruent and corresponding sides congruent
Same position Corresponding Sides
Corresponding Angles Same position
Third Angle Theorem If two angles of one triangle are to two angles of a second triangle, then the third pair of angles have to be congruent.
A B C D E F Ex 1: Write a congruence statement for the triangles. List all congruent sides and angles
Ex 2: Solve for x and y. G L M E P F H N 72 o 87 o 110 o 8m 10m (2x – 3)m (7y+9) o
Ex 3: Solve for x. T L M S R N 65 o 55 o (2x +30) o
Ex 4: Are these two triangles congruent? Explain. P Q M N R 92 o Sides: Angles: (given) (vertical angles) (3 rd angles thm) Yes, they are congruent because all sides and angles are congruent
Guided Practice p. 205 #1-9 Find a partner for Think, pair, share!!!