Question
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Answer
From the given figure,
$\angle DOC + 125^\circ = 180^\circ $[linear pair]
$\angle DOC = 55^\circ$
Now, in $\triangle$DOC,
$\angle DCO + \angle ODC + \angle DOC = 180^\circ$[angle sum property of a triangle]
$\angle DCO +70^\circ + 55^\circ=180^\circ$
$\angle DCO = 55^\circ$
Now, $\triangle ODC \cong \triangle OBA$ [given]
$\therefore \angle OAB = \angle OCD = 55^\circ$
$\angle DOC + 125^\circ = 180^\circ $[linear pair]
$\angle DOC = 55^\circ$
Now, in $\triangle$DOC,
$\angle DCO + \angle ODC + \angle DOC = 180^\circ$[angle sum property of a triangle]
$\angle DCO +70^\circ + 55^\circ=180^\circ$
$\angle DCO = 55^\circ$
Now, $\triangle ODC \cong \triangle OBA$ [given]
$\therefore \angle OAB = \angle OCD = 55^\circ$
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