We know that The inscribed angle Theorem states that t<span>he inscribed angle measures half of the arc it comprises. </span>so m∠D=(1/2)*[arc EFG] and m∠F=(1/2)*[arc GDE]
arc EFG+arc GDE=360°-------> full circle
applying multiplication property of equality (1/2)*arc EFG+(1/2)*arc GDE=180°