2. Consider the function f : R - R defined by f (2) = (10 sin(x), 23) (a) Prove that f is injective. You may assume that the function g : R - R defined by g(x) = x is injective, but you should state clearly where you use this fact. [Hint: For (a, b), (c, d) E R2, when is it true that (a, b) = (c, d)?] (b) Is f surjective? Explain your reasoning. 1