Oddly enough, on a computer, I have not seen secant, cosecant, or cotangent.

I have seen sin, cos, tan, arcsin, arccos, and arctan.

Though the arc functions will only have one parameter, so if this is homework, you’ll probably be avoiding the arcs and using secant and friends

Anyways:

sin ( angle )

Term	In this example
Parameter	Angle is the parameter. It’s in radians, so in Java you’ll use a conversion like Math.toRadians(a) on whatever number you’re going to use as an argument
Argument	If I were to call sin(Math.PI / 4) then I would be passing the argument π / 4 to the function.
	In other words, if a parameter is a question, then an argument is an answer. If a parameter is a coin slot, than an argument is the coin you choose to insert.
Operation	An operation is practically synonymous with “function”. It is performed on inputs to arrive at an output. However, usually in code, I hear “operation” used to describe things like /, *, and +. Things that have multiple inputs and a single output, all of the same form.

If someone is asking you, "which operation should you use in the body of function sin ( hyponetuse, opposite ) then I imagine the expected answer would be, / because

1. / is an operation, and because
2. opposite / hypotenuse will perform the division that yields the sine of whatever triangle those two sides belong to.