Docs about the trig functions.

doc-src/content/CHANGELOG.markdown

@@ -44,6 +44,9 @@ COMPASS CHANGELOG
   * `cos($number)` - Takes the cosine of the number.
   * `tan($number)` - Takes the tangent of the number.
   * `pi()` - Returns the value of π.
+  If you provide a number with units of `deg` then it will return a unitless number
+  after converting to radians. Otherwise, it assumes the number is a radian length measure
+  and passes the units along to the result.
 
 ### Rails
 

doc-src/content/reference/compass/helpers.haml

@@ -22,6 +22,7 @@ layout: core
   * [adjust-saturation()](/docs/reference/compass/helpers/colors/#adjust-saturation)
   * [append-selector()](/docs/reference/compass/helpers/selectors/#append-selector)
   * [color-stops()](/docs/reference/compass/helpers/color-stops/)
+  * [cos()](/docs/reference/compass/helpers/trig/#cos)
   * [elements-of-type()](/docs/reference/compass/helpers/display/)
   * [enumerate()](/docs/reference/compass/helpers/selectors/#enumerate)
   * [font-files()](/docs/reference/compass/helpers/font-files/)
@@ -33,7 +34,9 @@ layout: core
   * [inline-font-files()](/docs/reference/compass/helpers/inline-data/#inline-font-files)
   * [inline-image()](/docs/reference/compass/helpers/inline-data/#inline-image)
   * [nest()](/docs/reference/compass/helpers/selectors/#nest)
+  * [pi()](/docs/reference/compass/helpers/trig/#pi)
+  * [sin()](/docs/reference/compass/helpers/trig/#sin)
   * [stylesheet-url()](/docs/reference/compass/helpers/urls/#stylesheet-url)
   * [scale-lightness()](/docs/reference/compass/helpers/colors/#scale-lightness)
-  * [scale-saturation()](/docs/reference/compass/helpers/colors/#scale-saturation)
+  * [tan()](/docs/reference/compass/helpers/trig/#tan)
 

doc-src/content/reference/compass/helpers/trig.haml

@@ -0,0 +1,57 @@
+--- 
+title: Compass Trigonometric Helpers
+crumb: Trig
+framework: compass
+meta_description: Helper functions for working with angles.
+layout: core
+classnames:
+  - reference
+  - core
+  - helpers
+---
+%h1 Compass Trig Helpers
+
+:markdown
+  Trigonometric functions can help you manage complex calculations involving angles.
+  Or maybe they can be used to create pretty pictures. Who knows?
+
+
+#pi.helper
+  %h3
+    %a(href="#pi")
+      pi()
+  .details
+    %p
+      Returns the value of π.
+
+#sin.helper
+  %h3
+    %a(href="#sin")
+      sin($number)
+  .details
+    %p
+      Takes the sine of a number. If the number is unitless or has a unit of <code>deg</code>
+      then it will return a unitless result. Degrees will first be converted to radians.
+      If the number is any other unit, the units will be passed thru to the result,
+      and the number will be treated as radians.
+
+#cos.helper
+  %h3
+    %a(href="#cos")
+      cos($number)
+  .details
+    %p
+      Takes the cosine of a number. If the number is unitless or has a unit of <code>deg</code>
+      then it will return a unitless result. Degrees will first be converted to radians.
+      If the number is any other unit, the units will be passed thru to the result,
+      and the number will be treated as radians.
+#tan.helper
+  %h3
+    %a(href="#tan")
+      tan($number)
+  .details
+    %p
+      Takes the tangent of a number. If the number is unitless or has a unit of <code>deg</code>
+      then it will return a unitless result. Degrees will first be converted to radians.
+      If the number is any other unit, the units will be passed thru to the result,
+      and the number will be treated as radians.