## Thomas' Calculus 13th Edition

$4.6984$
The formula to calculate the arc length is as follows: $L=\int_{c}^{d} \sqrt {1+[f'(x)]^2} dx$ Now, $f'(x)=x \sin x$ Re-write the equation as follows: $L=\int_{0}^{\pi} \sqrt {1+(x \space \sin x)^2} dx$ After calculations using a calculator: $l=4.6984$