document.write( "Question 333685: I would like an explanation to this problem.
\n" ); document.write( "**use a half angle formula to find cos 22.5 degrees
\n" ); document.write( "Thanks for your help. \n" ); document.write( "

Algebra.Com's Answer #239117 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!

\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Since 22.5° is  of 45°, we substitute \r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "We take the positive result because cos(22.5°) is positive.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Multiply top and bottom of the complex fraction under the radical by 2:\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "That's the final result.  We check it by evaluating that as\r\n" );
document.write( ".9238795323 with a calculator and then finding the cosine of 22.5° \r\n" );
document.write( "and we find that it also has that same decimal value, .9238795323.\r\n" );
document.write( "\r\n" );
document.write( "Edwin

\n" ); document.write( "

\n" );