Question 234312
<pre><font size = 4 color = "indigo"><b>
{{{(Sin(y/2)+Cos(y/2))^2=1+Sin(y)}}}

Square the left side:

{{{Sin^2(y/2)+2*Sin(y/2)Cos(y/2)+Cos^2(y/2)=1+Sin(y)}}}

Swap the last two terms on the left side:

{{{Sin^2(y/2)+Cos^2(y/2)+2*Sin(y/2)Cos(y/2)=1+Sin(y)}}}


Use the identity {{{Sin^2(phi)+Cos^2(phi)=1}}} to replace
the first two terms by 1.

{{{1+2*Sin(y/2)Cos(y/2)=1+Sin(y)}}}

Use the identity {{{Sin(2*phi)=2*Sin(phi)*Cos(phi)}}} to replace
the second term on the left by {{{Sin(2*(y/2))}}} 

{{{1+Sin(2*(y/2))=1+Sin(y)}}}

{{{1+Sin(cross(2)*(y/cross(2)))=1+Sin(y)}}}

{{{1+Sin(y)=1+Sin(y)}}}

Edwin</pre>