If Jesus is God then why did he have to pray?

If Jesus is God then why did he have to pray?

Answer:

Because he was fully man:

For this reason he had to be made like his brothers in every way, in order that he might become a merciful and faithful high priest in service to God, and that he might make atonement for the sins of the people. Heb 2:17 NIV

We often forget the human divine nature of Jesus. What theologians call the Hypostatic union.

For further reading on this see Understanding the Incarnation By Matt Perman