Question 1129548
<pre>
{{{sin(2x)/(2sin(x))=cos^2(x/2) - sin^2(x/2)}}}

Use the identity: {{{cos^2(theta)-sin^2(theta)=cos(2theta)}}}
on the right side with {{{theta=x/2}}} to rewrite the right
side as cos(x).

{{{sin(2x)/(2sin(x))=cos(x)}}}

Now work with the left side.  [It's OK to do this, because you are
only working with one side AT A TIME, never BOTH sides together!!!]

Use the identity: {{{sin(2theta)=2sin(theta)cos(theta)}}} on the
left side:

{{{2sin(x)cos(x)/(2sin(x))=cos(x)}}}

Cancel:

{{{cross(2)cross(sin(x))cos(x)/(cross(2)cross(sin(x)))=cos(x)}}}

{{{cos(x)=cos(x)}}}

Edwin</pre>