Question 1082416
Amplitude is 1/2 the range,
{{{A=(1/2)(80-40)=(1/2)(40)=20}}}
Mean value is the average of the two extremes,
{{{T[m]=(80+40)/2=120/2=60}}}
Time to complete one cycle  (period) is,
{{{t[P]=12+12=24}}}
So the period is {{{P=(2pi)/24=pi/12}}}
Doesn't start at mean value, it starts at the lower extreme so there is a phase angle. Dial it back one quarter period.
 
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So putting it all together,
{{{H=60+20sin((pi/12)t-pi/2)}}}
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