How to Graph the Cosine Function?

A step-by-step guide to graphing the cosine function

Cosine is one of the primary mathematical trigonometric ratios. The cosine can be defined as the ratio of the length of the base to the length of the hypotenuse in a right triangle.

\(\color{blue}{cos\:x\:=\frac{Adjacent\:Side}{Hypotenuse}=\frac{Base}{Hypotenuse}\:}\)

where \(x\) is the acute angle between the base and the hypotenuse.

A cosine graph or \(cos\) graph is a top-down graph just like a \(sin\) graph. The only difference between a \(sin\) graph and a \(cos\) graph is that a sine graph starts at \(0\) while a cos graph starts at \(90\) (or \(\frac{\pi }{2})\). The \(cos\) plot given below starts at \(1\) and decreases to \(-1\) and then starts increasing again.