Q3 (16 points) Prove the following: (a) [5 pts] cosh (sinh ¹ x) = √√√x² + 1; (b) [6 pts] arctan (tanh x) = sech(2x). dx (c) [5 pts] Verify the function y cosh x satisfies the equation d² y dx2 = 1+ ( dy dx 2