The Cosine Graph

The cosine graph is similar in shape to the Sine graph. Like the sine function, the cosine function also appears in the study of geometry in its connection with right angled triangles.

The Cosine measures the ratio between the adjacent side and the hypotenuse. It is defined as follows:

$cos(x)=\dfrac{adjacent}{hypotenuse}$

As with Sine graphs, Cosine graphs have more than one solution for each value of $cosx$. We can find the angle which corresponds to a $cosx$ value using the $cos^{-1}$ function.

For example, the corresponding angle for $cosx=1$ is:

$cos^{-1}(1)=0$

This is known as the principle value. We can then use the symmetry of the graph to find other points which also give this value.