The amplitude of the functions going to be the number in front of the trig function, in this case 3, the period of the function. A regular. For a sine graph, is 2π, and that's always going to get divided by the coefficient on the X term. So 2π / 2π / 365 is going to give us the new. So 2π divided by is the same thing as multiplying by its reciprocal. The 2π's cancel and we get 365. How many hours of daylight are there on the longest day of the year? Well, if we know the amplitude's three, we know the highest it's ever going to go is 3, and the lowest it's ever going to go is -3. But we also have a vertical shift of 12. So 12 + 3 is going to be the highest we ever go. The lowest we ever go is going to be that vertical shift 12 -, 3. So we get 15 and we get 9. For the highest and the lowest, we need to figure out what the vertical shift is. No, the phase shift. So the easiest way I can tell you to do that is to take the parenthesis portion and set it equal to 0 to figure out how we're shifting. If we multiply each side by 36365 / 2π, we'd get X - 79 = 0 or X = 79. So we know that our graph is going to get moved over to 79. We're going to be up at 12, we're going to go higher than 12 by three, and we're going to go lower than 12 by three, 365 later. We're going to be at the end to find these other points. One way to do it, there are many, is to take that 365, the period and divide by 4 and so 79 plus 365 / 4. And then the next one is 79 plus two 360 fives over 4, which would really be 365 / 2, the next 179 plus three 360 fives over 4, and then the last one the 79 + 4, 360 fives over four, or just 79 + 365.