1. The amplitude is 1; The amplitude is the number that appears before the cos( theta), and that is 1.
2. The period is how often it repeats, and the is 2π radians or 360°
3. The domain is all real numbers, because for all values of x, there's a value of y.
4.The range is [-1,1] because the y values go up to and including 1 and down to and including -1
5. The x-intercepts are at π(1/2 ± n), where the angle is in radians and n is any integer, positive or negative. In degrees, it is 180(1/2 ± n)°.
The graph of the cosine function has even symmetry since cos(- (theta)) = cos(theta). On the unit circle, x = cos(theta), and because the unit circle is symmetrical across the x-axis, an arc length of () and (-) produce the same x coordinate.