document.write( "Question 65913: 
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document.write( "Prove that this equation is an identity:\r\n" );
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document.write( "(sinx + cscx)² + (cosx + secx)² º tan²x + cot²x + 7
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Algebra.Com's Answer #46684 by Edwin McCravy(20056)\"\" \"About 
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Answer by Edwin McCravy(279)
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document.write( "Prove that this equation is an identity:\r\n" );
document.write( "                                                   ?\r\n" );
document.write( "                   (sinx + cscx)² + (cosx + secx)² º tan²x + cot²x + 7\r\n" );
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document.write( "We will work only with the left side, since\r\n" );
document.write( "it looks more complicated than the right side.\r\n" );
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document.write( "Square the two binomials on the left\r\n" );
document.write( "                                                   ?\r\n" );
document.write( "   sin²x+2sinx·cscx+csc²x + cos²x+2cosx·secx+sec²x º tan²x + cot²x + 7\r\n" );
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document.write( "Replace the sin²x + cos²x by 1  \r\n" );
document.write( "                                                   ?\r\n" );
document.write( "       1 + 2sinx·cscx + csc²x + 2cosx·secx + sec²x º tan²x + cot²x + 7\r\n" );
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document.write( "Replace cscx by 1/sinx and secx by 1/cosx \r\n" );
document.write( "                                                   ?\r\n" );
document.write( "   1 + 2sinx·1/sinx + csc²x + 2cosx·1/cosx + sec²x º tan²x + cot²x + 7\r\n" );
document.write( "                                                   ?\r\n" );
document.write( "                   1 + 2(1) + csc²x + 2(1) + sec²x º tan²x + cot²x + 7\r\n" );
document.write( "                                                   ?\r\n" );
document.write( "                                 5 + csc²x + sec²x º tan²x + cot²x + 7\r\n" );
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document.write( "Use identity csc²x º 1 + cot²x to replace csc²x\r\n" );
document.write( "and sec² º 1 + tan²x to replace sec²x\r\n" );
document.write( "                                                   ?\r\n" );
document.write( "                         5 + 1 + cot²x + 1 + tan²x º tan²x + cot²x + 7   \r\n" );
document.write( "                                                   ?\r\n" );
document.write( "                                 7 + cot²x + tan²x º tan²x + cot²x + 7\r\n" );
document.write( "                                                   Ö     \r\n" );
document.write( "                                 tan²x + cot²x + 7 º tan²x + cot²x + 7\r\n" );
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document.write( "Edwin
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