Answer
$\pi$
Work Step by Step
Flow $=\int_C F(r(t)) \dfrac{dr}{dt}(dt)$
and $ \dfrac{dr}{dt}=- \sin t i+0j+\cos tk$
Then work done $=\int_0^{\pi}(- \sin t i+0j+\cos tk)((\cos t- \sin t) i+0j+\cos tk) dt$
or, $= \int_0^{\pi}\dfrac{-1}{2} \sin 2t +1 dt$
or, $=[ \dfrac{1}{4} \cos 2t +t]_0^{\pi}$
or, $=\pi$
