The depth of water(d metres) in a harbour is given by the formula d = a+bsin(ct) where a, b and c are constants, and t is the time in hours after midnight. It is known that both b and c are non-zero and 20<c<35. If t=midnight, d=5; if t=noon, d=5; if t=1300, d=7; and if t=1400, d=8.46. Using the pieces of information, find the values of a,b and c.
I already found the a, which is 5.
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