Use the Squeeze Principle to establish the limit of the following functions (a) lim(x,y) -> (0,0) f(x,y), where f(x, y) = y^2 (1-сos 2x) / x^4+y^2 (a) lim x->0 f(x), where f(x) = 2 + x^2 e^sin(1/x).