document.write( "Question 901450: Explain why \"cos%5E%28-1%29%28-0.9%29\" is not a negative number. \n" ); document.write( "
Algebra.Com's Answer #546751 by Edwin McCravy(20059)\"\" \"About 
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document.write( "Since the cosine function is not one-to-one, its inverse would not be a\r\n" );
document.write( "function.  So cos-1(x) was defined so that it would be a function by\r\n" );
document.write( "restricting its domain to [0,p] or {y|0≦y≦p}, which is never negative.\r\n" );
document.write( "Therefore by definition cos-1(-0.9) is between 0 and p, actually in \r\n" );
document.write( "quadrant II between \"pi%2F2\" and p, approximately 2.69 (radians).\r\n" );
document.write( "Edwin
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