Exercise 3.3.34, 3.5.28 were graded out of 3 points, and the rest out of 2 points.
To compute the limit in 3.3.48, you cannot use L'Hôpital's rule, as it hasn't seen yet in class.
In 3.3.34, remember that sin(x) = cos(x) has infinitely many solutions, since sin and cos are periodic functions.