4-2+Congruency

4-2 Congruence and Shapes (including polygons) 2 geometric figures are congruent if they have exactly the same size and shape. When two figures are congruent there is a correspondence between there angles and sides such that corresponding angles are congruent and corresponding sides are congruent Since triangle QPR is congruent to triangle JLK we can say that <Q is congruent to <J, <P is congruent to <L, <R is congruent to <K, and segment QP is congruent to segment JL segment PR is congruent to segment LK and segment RQ is congruent to segment KJ.

If we know the side and angle measures of triangle QPR we can figure out the side and angle measures of triangle JLK.

Third Angles Theorem: If two angles if one triangle are congruent to two angles of another triangle then the third angles are also congruent.

Other properties of congruent triangles: Reflexive property of congruent triangles- every triangle is congruent to itself. Symetric property of congruent triangles- if triangle QPR is congruent to triangle JLK then triangle JLK is congruent to triangle QPR. Transitive property of congruent triangles- If triangle QPR is congruent to triangle JLK and triangle JLK is congruent to triangle ABC then triangle QPR is congruent to triangle ABC