I think its irrational bc if you put it as the squareroot of 329, it results in neverending decimals.
18^2=324+5=329
Y=Acos(p)+m, A=amplitude, p=period, m=midline, in this case:
A=1/2, p=360(t/12)=30t, m=(10-9)/2+9=9.5 so
h(t)=(1/2)cos(30t)+9.5
I think the answer is C hope this would help you
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