On a graph the amplitude is one half the overall height. The unit circle has a max/min value of y = 1, -1, making the amplitude 1. Period: 2?.
The pattern of the graph will repeat itself for each increment of 2? that occurs. In the unit circle, 2? is the length it takes in order to make one full revolution. Domain: (??,?).
The domain of the sine function is any input value that theta can represent. Since you can go around the unit circle an infinite number of times in both directions (counterclockwise and clockwise), the domain can be any real number. Range: -1, 1. The range contains all of the possible y values in the sine function.
As pointed out earlier, the y values present in the unit circle reach their largest at 1 and lowest at -1, thus providing the range. X-intercepts: These occur at points where the the line of the graph intersects the x-axis. In this case, you notice the x-intercepts are multiples of ?, which can be written as x = n? and indicates where they are found.