Answer variants:
\(\angle OPN\)
bisected angles
two
\(\angle QON\)
common
\(OM\)
 
58.svg
 
\(OM\) is the angle bisector of \(\angle POQ\). \(NP\) and \(NQ\) meet \(OA\) and \(OB\) respectively at \(57^\circ\). Complete the missing fields to prove that the triangles \(OPN\) and \(OQN\) are congruent to each other.
 
Proof:
 
We know that
 
 is the angle bisector of \(\angle POQ\).
 
Hence, \(\angle PON = \) 
 .
 
[Since the angles mentioned in the previous step are
]
 
Now, let us consider the triangles OPN and OQN.
 
 
 \(= \angle OQN =\) \(57^\circ\) [Given]
 
Also, \(ON\) is 
 to both the triangles \(OPN\) and \(OQN\)
 
Here, one corresponding pair of sides and 
 corresponding pair of angles are equal.
 
Thus by  congruence criterion, \(OPN\) \(\cong\) \(OQN\).