Question 969742
<pre>
You need to know three things:

1. The formula you need is:

{{{cos(alpha)cos(beta)-sin(alpha)sin(beta)}}}{{{""=""}}}{{{cos(alpha+beta)}}}

Substitute {{{pi/12}}} for {{{alpha}}} and {{{pi/6}}} for {{{beta}}} in that
formula.

2. You need to know how to add the two fractions you'll have in the right side:

{{{pi/12+pi/6}}} by getting a common denominator of 12, and reduce it.

3. Finally you need to know the trig ratios for the special angles:

   |  <font face="symbol">p</font>/6 |  <font face="symbol">p</font>/4 | <font face="symbol">p</font>/3  
----------------------      
sin|  1/2 | &#8730;2/2 |&#8730;3/2    
---|------|------|----
cos| &#8730;3/2 | &#8730;2/2 | 1/2

Good luck.  Need any more help?  If so, ask me in the thank-you note form below.
I'll get back to you.

Edwin</pre>