54/x = 6...multiply both sides by x
54 = 6x...divide both sides by 6
54/6 = x
9 = x
In the standard form of the equation
The middle line =k
For our given problem
f(t) = 40cos (80t + 20)
On comparison we get k=0
Hence middle line=0
the difference in depth is 3 feet, you can find this by the equation 14-11
Answer:240 rotations
Step-by-step explanation: 1 rotation/45 seconds * 60 seconds / minute * 60 minutes / hour * 3 hours = 3600*3/45 = 240 rotations