The length of the day in Lagos, Nigeria (in minutes), ttt days since the beginning of the year can be estimated by this formula: \qquad L(t) = 727+22\sin \left(\dfrac{2\pi (t - 80.75)}{365}\right)L(t)=727+22sin( 365 2π(t−80.75) )L, left parenthesis, t, right parenthesis, equals, 727, plus, 22, sine, left parenthesis, start fraction, 2, pi, left parenthesis, t, minus, 80, point, 75, right parenthesis, divided by, 365, end fraction, right parenthesis. When is the longest day of the year? Give an exact answer.

The longest day of the year is day 172  

Step-by-step explanation:

Since the length of day is L(t)=727+22sin[2π(t−80.75)/365], the maximum length of day is obtained when sin[2π(t−80.75)/365] is at its maximum value which is 1. So. sin[2π(t−80.75)/365] = 1

We now solve this to find the day at which this maximum value occurs.

sin[2π(t−80.75)/365] = 1

[2π(t−80.75)/365] = sin⁻¹(1)

[2π(t−80.75)/365] = π/2

dividing both sides by 2π/365, we have

[2π(t−80.75)/365] ÷ 2π/365 = π/2 ÷ 2π/365

t−80.75 = 365/4

t−80.75 = 91.25

t = 91.25 + 80.75

t = 172

The longest day of the year is day 172