7.7 SUMMARY:
i) Two line segments are congruent only when their lengths are equal .
PQ = RS
ii) Two angles are congruent only when their degree measures are equal . ∠ABC ≅ ∠PQR .
iii) The symbol ‘≅ is used to represent congruence .
* In case ΔABC ≅ ΔDEF
D corresponds to A or D ↔ A
E corresponds to B or E ↔ B
F corresponds to C or F ↔ C .
In congruent triangles , corresponding parts are equal and we write in short ‘c.p.c.t.’ ”For Corresponding Parts of Congruent Triangles ”.
I. A triangle in which two sides are equal is called an isosceles triangles .
II. Angles opposite to equal sides of an isosceles triangle are equal .
III. The sides opposite to equal angles of a triangle are equal .