[填空题]
When a coin is thrownp-9ckqcp 6 hlf ltefh(/0*qo 6 from the top of a skyscraper, its height ab epsf3 6gy(*qgcgyh jz,+tc8k2dv5 0n ove the ground after t pf,*+n ggdhc80ktc6z5g( y yev3 q2sj seconds is given by s(t)=$at^2$+bt+c, where a,b,c∈R and s(t) is measured in metres. After 11 second, the coin is 179.3 m above the ground; after 2 seconds, 188.2 m; after 66 seconds, 159.8 m.
1.(1)Write down a system of three linear equations in terms of a, b and c.
(2)Hence find the values of a, b and c. a = b = c =
2.Find the height of the skyscraper. s = m
3.Find the time it takes for the coin to hit the ground. t ≈