If we have our statement p then q:

The inverse is inverting the signs think of i as the square root of -1. You are negating each element.

~p -> ~q

Converse, reverse.

q -> p.

Once you remember those, just remember that the contrapositive is converse and inverse combined.

~q -> ~p

In Calculus II we learn the wretched “Trigonometric substitution” and it can be hard to remember them. I came up with this little pneumonic device to help me out. Is it good? Not at all. Did it help? Yes, it did.

a^2-x^2 = sin^2x: Sine gets the mine.

a^2+x^2 = tan^2x: Remember the A in tAngent and the A in Add. Taddgent.

x^2-a^2 = sec^2x: She cant keep that constant = secant keep that constant.

These are stupid but I hope that they help.