How did Shi Huangdi enforce his control over a widespread territory in China? He used the philosophy of Confucianism which discouraged trust in the people who served in the
government.
He used the philosophy of Legalism which required a ruler to be fair and care for all people as if they were
his family.
He used the philosophy of Confucianism which focused on order in relationships and respect and honor for
superiors.
He used the philosophy of Legalism which gave absolute power to the king and encouraged strict laws and
harsh punishments

He used philosophy of Legalism which gave absolute power to the king and encouraged strict laws and harsh punishments.

Explanation:

Philosophy of Legalism is based on the assumption that Human beings are inherently selfish and will always do things to serve their own interest.

In order to prevent the selfish human from causing chaos, a strong legal system  is needed in order to create laws that will strongly punish those who conduct misbehaviors. That central system need to be controlled by a body of government that possess higher authority than any other institution.

This is why supporters of legalism tend to support giving absolute power to the Central government (Kings and his trusted people;.)

i dont know sorry why dont you looking it up on google