3cosx
3cosx refers to the mathematical function of three times the cosine of x. The cosine function, denoted as cos(x), is a fundamental trigonometric function that relates an angle of a right-angled triangle to the ratio of the length of the adjacent side to the hypotenuse. In the context of the unit circle, cos(x) represents the x-coordinate of a point on the circle at an angle x radians from the positive x-axis.
The function 3cosx is a vertical stretch of the basic cosine graph by a factor of 3.
The domain of 3cosx is all real numbers, as the cosine function is defined for any angle.