[填空题]
The Singapore Flyer is a giant observation wheel in Singapore wd v zwxx26g0soq qum g5qgd,a;7t8 6(jith diamete7 bj0k *qutw9hr of 150 metres. The wheel rowuht 9 bkqj07*tates at a constant speed 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
