[填空题]
The height, h metres, 5 dla*p ) .z3vf(aunfrof a seat on a Ferris ah7f,9oehw/1oxczo-wheel after t minutes is given by
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$h(t)=-23.5 \cos (0.4 t)+25, \text { for } t \geq 0 \text {. }$
1. Find the initial height of the seat.
Once a passenger's seat is more than 30 m above the ground, there are no trees in view and they can take unobstructed photographs of a nearby city.
2. Given that passengers only complete one rotation on the Ferris wheel, calculate how long they can take unobstructed photographs of the nearby city.
