To "determine" something means to figure it out or make a decision about it. "Determine" is a formal word, so you can use it in situations like when describing legal decisions:

The judge determined that Medco was responsible for the patients' medical issues. They were required to pay a large settlement.

Or you can use it in a business setting:

Have they determined when the merger will take place?

After "determined", you can use a clause like in the previous examples, or a noun:

Once we've determined the cause of the outage, we'll send a full report.