To solve for the trigonometric functions of x, we need to recall the ratios they represent as shown below.
sin x = O/H
cos x = A/H
tan x = O/A
where O stands for opposite, A for adjacent, and H for hypotenuse. So, for example, the sine of x is equal to the side opposite of angle x over the hypotenuse. The same goes for cosine and tangent. Using the diagram attached, we have the expressions of the trigonometric functions as shown below.