<math>\cos \theta = \sin \left(\frac{\pi}{2} - \theta \right) = \frac{1}{\sec \theta}\,</math>
==Cosine Graph==
The basic cosine graph is as follow:
{| style="background:none"
|
{| class="wikitable" style="text-align:center"
|-
!x values
!y values
|-
|width="50%"|0
|width="50%"|1
|-
|π/2
|0
|-
|π
| -1
|-
|3π/2
| 0
|-
|2π
|1
|}
|[[Image:Cosine-pi.jpg|350px]]
|}
That would be a full period of the graph - as 2π [[radians]] is equivalent to one circle. The graph continues in that pattern.
[[Category:Trigonometry]]