Respuesta :

calculista
the correct question in the attached figure

we know that
the inscribed angle measures half of the arc it comprises.
then
m∠YAB=(1/2)*m∠BY-------------> m∠YAB=(1/2)*24°=12°
m∠YAC=90°-m∠YAB=90°-12°=78°

the answer is the option C) 78°    
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