document.write( "Question 998441: Find the exact value of cos 75 degree \n" ); document.write( "

Algebra.Com's Answer #616229 by ikleyn(52852) $\"\"$ $\"About$

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\n" ); document.write( "Find the exact value of cos 75 degree
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\n" ); document.write( "\n" ); document.write( "First, cos(75°) = sin(15°)     (the reduction formula).\r
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\n" ); document.write( "\n" ); document.write( "Next, sin(15°) = $\"sin%28%2830%5E0%29%2F2%29\"$ = $\"sqrt%281-cos%2830%5E0%29%29%2F2%29\"$ =       (formula of half-argument for sine) = \r
\n" ); document.write( "\n" ); document.write( "= $\"sqrt%28%281-sqrt%283%29%2F2%29%2F2%29\"$ = $\"sqrt%28%282-sqrt%283%29%29%2F4%29\"$ = $\"sqrt%282-sqrt%283%29%29%2F2\"$ .\r
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\n" ); document.write( "\n" ); document.write( "Answer. cos(75°) = $\"sqrt%282-sqrt%283%29%29%2F2\"$ .\r
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\n" ); document.write( "\n" ); document.write( "See the lessons \r
\n" ); document.write( "\n" ); document.write( "    - Trigonometric functions of half argument and \r
\n" ); document.write( "\n" ); document.write( "    - Trigonometric functions of half argument - Examples\r
\n" ); document.write( "\n" ); document.write( "in this site.\r
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