The trig functions that you need to deal with are
Sine
Cosine
Tangent
Cotangent
Cosecant
Secant
You need to write a single expression using all six trig functions such that the value of the expression equals 3.
To make this as simple as possible, the first thing I would do is look up the values of these functions and identify which ones are equal to either 1/2 or 1.0 or 2.0
sin(30º) = 1/2
sin(90º) = 1
cos(0º) = 1
cos(60º) = 1/2
tan(45º) = 1
csc(30º) = 2
csc(90º) = 1
sec(0º) = 1
sec(60º) = 2
cot(45º) = 1
If we only had to use three trig functions (sin, cos, tan), one possibility is
tan(45º) + cos(0º)/sin(30º) = 1 + 1/(1/2) = 1 + 2 = 3
noticed how I chose one each of the required functions and the operations so that the result = 3.
Now it is up to you to figure out how to combine all six trig functions so that they equal zero. There are many possibilities for you to choose from..