[填空题]
The Singapore Flyer is a sfzv2q:ii8ti1q sr9 ui p 2(d2(y*l idgiant observation wheel in Singapore with d 54pmxwb pm,hd)e6zki.2 ni)b iameter of 150 metres. The wheel rotates at a constant speez khw i6b2xe)m,m) .pnp5bd4id and completes one rotation in 32 minutes. The bottom of the wheel is d metres above the ground.
A seat starts at the bottom of the wheel.
1. After 16 minutes, the seat is 165 metres above the ground. Find d .
After t minutes, the height of the seat above the ground is given by
$h(t)=90+a \cos \left(\frac{\pi}{16} t\right), \text { for } 0 \leq t \leq 64 $.
2. Find the value of a .
3. Find when the seat is 60 metres above the ground for the third time. min
