The curve has equation

.

a] use the substitution to evaluate the arc length of correct to 2 decimal places.

b] The arc of joining the points and is rotated through four right angles about the x-axis. Find the area of the curved surface generated correct to 2 decimal places.

I've done part a] - got 2.96.

Part b] is giving me significant trouble though. I write the integral as

and from here, I've tried a variety of techniques - I made the term into and used the rule but the answer was wrong, and I tried the same hyperbolic substitution, which also gave me a wrong answer. I know this because the answer is written down on a sheet with no working to show it was obtained. Please could you suggest a suitable way to approach the question? Any help is greatly appreciated