Hi I hope this is in the correct forum

My teacher has told me I will need to be able to do these in my up and comping exam later this month. He covered the topic a while ago but I didn't quite understand. Here is an example I have.

Express the polar point (6, 120 °) in rectangular coordinates.

I have no idea how to start doing these? Guidence of any kind would be wonderful.

Regards Lakitu