Graph of y = cosx

Graph:

From the graph it is clear that the curve repeats itself every 360^o (2prad). This fact is expressed by the statement that the function has a period of 360^o (2p radians). In symbols we write cos(x + 360^o.n) = cos(x + 2pn) = cos x where n is a positive or negative integer.

From the graph we also observe that cosx does not pass through the origin. The maximum and minimum values of cosx are +1 and -1 respectively. As x increases from 0^o to 90^o cosx decreases from 1 to 0, as x increases from 90^o to 180^o cosx decreases from 0 to -1, as x increases from 180^o to 270^ocosx increases from -1 to 0, as x increases from 270^o to 360^o cosx increases from 0 to 1. Cosx is period and has a period 2p.