(a) Find the exact area of the region under the graph of $y=\cos(x)$ from $x = 0$ to $x = b$ (where $0 \le b \le \pi/2$) by using a computer algebra system to evaluate the sum and limit that arise in the computations.

Value of limit =

(b) What is the value of the limit if $b=\pi/2\,?$

Value of limit =