Question 978446
<pre>

{{{cos^2(x)+2cos(x)+1}}}{{{""=""}}}{{{"0"}}}

Use u-substitution:

Let u = cos(x)

{{{u^2+2u+1}}}{{{""=""}}}{{{"0"}}}

{{{(u+1)(u+1)}}}{{{""=""}}}{{{"0"}}}

{{{(u+1)^2}}}{{{""=""}}}{{{"0"}}}

u+1 = 0
  u = -1

Substitute cos(x) for u

cos(x) = -1

     x = <font face="symbol">p</font>

Edwin</pre>