Implicit definition of a function:
Defining a function by conditions it satisfies rather than by an explicit
formula or algorithm for computing it.
Example: define y(x) by x2 + y2 =1 and y > 0.
Defining a function as the inverse of another is an implicit definition.
1.8 How much of this was familiar to you?
1.9 The statement cos x is implies
what about arccos y and arcsin y? Solution
1.10 Invent a problem to go here.