docs: fixes #873

Author: boriel

docs/cos.md

@@ -14,7 +14,7 @@ Argument must be a numeric expression in radians units. Returned value type is [
 
 ## Examples
 
-```
+```basic
 REM Cosine value
 PRINT "Cosine value of a is "; COS(a)
 ```
@@ -30,4 +30,4 @@ PRINT "Cosine value of a is "; COS(a)
 * [SIN](sin.md) and [ASN](asn.md)
 * [TAN](tan.md) and [ATN](atn.md)
 * [ACS](acs.md)
-*  Faster library option for lower accuracy trigonometry for games: [FCOS](fsin.bas.md)
+*  Faster library option for lower accuracy trigonometry for games: [FCOS](library/fsin.bas.md)