Is it correct to call an Apple Mac computer a PC (Personal Computer)
Solution 1:
I wouldn't consider you to be wrong (a Mac is a personal computer), but it is definitely the case that some people might be confused by using the terms in that way and it would then require further explanation. Because of that, I'm not sure there's really a definite answer to this as it will depend on the context and the knowledge of the reader. If in doubt, go for whatever phrasing is least likely to cause confusion.
I believe the term "PC" became the generally used expression as it stemmed from "IBM-compatible PC", which gradually became more and more mainstream. However you could also argue (correctly) that a modern Mac is also an IBM-compatible PC, since they use the same CPU architecture and so on now - just to add another level of confusion ;)
Solution 2:
It wouldn't make you wrong.
However, it would mean that many people may be confused about your statement, or they'd think you were making a point through your choice of language. At least that has been my experience. If that is your intention, then call your "Mac" a "PC".
Solution 3:
Words like "personal computer", "mini computer", "micro computer" etc. had a meaning in the 1970s and 1980s which is almost forgotten now. At first the whole notion of "personal computer" was a novelty. Nowadays almost all computers are "personal computers" in the sense that the word originally meant, and most people don't even know what a "mini computer" or "micro computer" might refer to. In the 1980s a Mac would have been referred to as a "personal computer" but I'm not sure why you would want to, any more than you would want to refer to it as a "micro computer". If you have to call it something, then calling it a "computer" is good enough.