Some people advise that in very cold weather, you should keep the gas tank in your car more than half full. Irene's car had 6.5 gallons in the 15-gallon tank on the coldest day of the year. Irene filled the tank with gas that cost $3.80 per gallon. How much did Irene spend on gas? Fast Please

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.