The period is [2(pi)] / |b|
so, it would be 2pi / pi/5 = 10
for the second part, just plug in 10 where the "t" is.
400sec(10pi/5) or 400sec(2pi)
Sec = 1 / cos
SO, you get 400*(1/cos(2pi)) = 400* 1/1 = 400. since cos(2pi) = 1
so you get 400 as your answer
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