A point performs damped oscillations according to the law x=a0e−βtsinωt.x=a_{0} \mathrm{e}^{-\beta t} \sin \omega t .x=a0e−βtsinωt. Find: (a) the oscillation amplitude and the velocity of the point at the moment t=0t=0t=0 (b) the moments of time at which the point reaches the extreme positions.