How do I apologize to my professor?

I missed our midterm because I felt sick. I probably could have made it, but truthfully, I didn't know our midterm was that day. I went to the doctor and I was diagnosed with strep throat, so in a way, maybe it was good that I didn't go to cl. How can I apologize to him through an e-mail, and how do I ask him if I can take the midterm?