\(KLMN\) is a quadrilateral in which \(KN = LM\) and \(∠ NKL = ∠MLK\).
 
Demonstrate that:
 
(i) \(∆ KLN≅ ∆ LKM\)
 
(ii) \(LN= KM\)
 
(iii) \(∠ KLN= ∠ LKM \).
 
ar3-tri-40 - Copy.png
 
Proof
 
(i) Considering two triangles \(ΔKLN\) and \(ΔLKM\).
 
Here, \(KN =\) [Given] ----(1)
 
\(∠ NKL = ∠\) [Given] ---(2)
 
\(KL=KL\) [Common side] ---(3)
 
Therefore, by congruence rule\(ΔKLN ≅ ΔLKM\)
 
Hence, we proved.
 
 
(ii) Since \(ΔKLN ≅ Δ\) [By SAS Congruence rule]
 
So, by , \(LN = KM\) 
 
Hence, we proved.
 
 
(iii) Since \(ΔKLN ≅ ΔLKM\) [By SAS Congruence rule]
 
So, by \(∠KLN= ∠LKM\)
 
Hence, we proved.