He temperature of a chemical reaction ranges between 30 degrees celsius and 70 degrees celsius. the temperature is at its lowest point when t = 0, and the reaction completes 1 cycle during a 10-hour period. what is a cosine function that models this reaction?
f(t) = 20 cos 10t + 50
f(t) = 50 cos 10t + 20
f(t) = −50 cos pi over 5 t + 20
f(t) = −20 cos pi over 5 t + 50