1. As part of a quality control test, a lifejacket is thrown into the sea.

The height, $h$ m, of the lifejacket above or below sea level $(h=0)$, at time $t$ seconds after first hitting the water, is modelled by the equation $h=-{e}^{-0.6t}$sin $2t$

(i) Find the height of the lifejacket after 1.5 seconds. Is the lifejacket above or below sea level at this point in time?

(ii) Excluding the case when $t=0$find the value of $t$ the first time the lifejacket is at sea level.