In each of the given pairs of triangles of Fig. 6.42, applying only ASA congruence criterion, determine which triangles are congruent. Also, write the congruent triangles in symbolic form.
Formula Used/Theory:-
ASA congruence criterion is in which 2 angles and a side between them are equal in both the triangles
(a) ∠A = ∠Q
But ∠B≠∠P
∴ Δ ABC and Δ PQR are not congruent
Result:- Δ ABC and Δ PQR are not congruent
(b) ∠ABD = ∠BDC
∠ADB = ∠DBC
BD = BD (common in both triangle)
∴ Δ ADB and Δ CBD are congruent by ASA
∆ADB ≅ ∆CBD
Result:- Δ ADB and Δ CBD are congruent by ASA
(c) ASA congruence criterion is in which 2 angles and a side between them are equal in both the triangles
∠X = ∠L
∠Y = ∠M
XY = ML
∴ Δ XYZ and Δ LMN are congruent by ASA
∆XYZ ≅ ∆LMN
Result:- Δ XYZ and Δ LMN are congruent by ASA
(d) → Angle sum property
Sum of all angles of triangle is 180°
By angle sum property
∠A + ∠B + ∠C = 180° ∠D + ∠E + ∠F = 180°
Equating both
We get;
∠A + ∠B + ∠C = ∠D + ∠E + ∠F
As ∠B = ∠F
∠A = ∠D
Cancelling out we get, ∠C = ∠E
∠C = ∠E
∠B = ∠F
BC = FE
∴ Δ ABC and Δ DFE are congruent by ASA
∆ABC ≅ ∆DFE
Result:- Δ ABC and Δ DFE are congruent by ASA
(e) In Δ PNO and Δ MNO
∠PNO = ∠MON
∠MNO≠∠PON
ON = ON (common in both triangles)
∴ Δ MNO and ΔPON are not congruent by ASA
Result:- ∴ Δ MNO and ΔPON are not congruent by ASA
(f) ∠D = ∠C
∠AOD = ∠COB
OD = CO
∴ Δ ADO and Δ BCO are congruent by ASA
∆ADO ≅ ∆BCO
Result:- Δ ADO and Δ BCO are congruent by ASA