In the month of June, the temperature in Johannesburg, South Africa, varies over the day in a periodic way that can be modeled approximately by a trigonometric function.
The lowest temperature is usually around 3°C, and the highest temperature is around 18°C. The
temperature is typically halfway between the daily high and daily low at both 10 a. m. and 10 p. m., and
the highest temperatures are in the afternoon.
Find the formula of the trigonometric function that models the temperature T in Johannesburg t hours
after midnight. Define the function using radians.