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^\circ C3
∘
C3, degrees, C, and the highest temperature is around 18^\circ C18
∘
C18, degrees, C. The temperature is typically halfway between the daily high and daily low at both 10\text{ a. m.}10 a. m.10, start text, space, a, point, m, point, end text and 10\text{ p. m.}10 p. m.10, start text, space, p, point, m, point, end text, and the highest temperatures are in the afternoon.
Find the formula of the trigonometric function that models the temperature TTT in Johannesburg ttt hours after midnight. Define the function using radians.