The sound level of a fire alarm siren follows the rule
A(t)=6sin πt+80 where A is the sound level measured in decibels (dB) and t is the time in seconds.
a) what is the maximum sound level the siren can reach?
b) How long does it take for the sound to reach its maximum level for the first time?
Maths question
2007-05-18 6:47 am
回答 (1)
2007-05-18 6:55 am
✔ 最佳答案
a) A is max when sin πt is max = 1, so A max = 6 + 80 = 68 dBb) when sin πt = 1 first time, πt = π/2 ==> t = 0.5 second.
2007-05-17 23:05:00 補充：
a) 6 80 = 86 dB
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