All trigonometric functions can be derived from a simple picture using the (unit) circle and similar triangles.
The value of any trigonometric function can found as a combination of values of any one trigonometric function evaluated at some related angles.
For example:
cosine and sine are related via: cos(Θ) = sin(90°-Θ)
etc...

a) Find how all of the functions in the applet can be written in terms of only sine.
Note: These functions are normally written as
sine = sin
chord = crd
tangent = tan
secant = sec
b) Complete the diagram to include the complementary trigonometric functions. These functions are normally written as
cosine = cos
cotangent = cot
cosecant = csc
Hints:
You can understand all of the relations by using similar triangles.
The value of a complementary function is the value of the function evaluate at the complementary angle.