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document.write( "We plot those given points and sketch in a rough sketch of the\r\n" );
document.write( "hyperbola. All \"conic\" graphs curve around their focal points.\r\n" );
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document.write( "The equation of all hyperbolas that open right and left have equations,\r\n" );
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document.write( "where (h,k) is the center, \"a\" is the distance between the center and\r\n" );
document.write( "either vertex. \"c\" is the distance between the center and either focal\r\n" );
document.write( "point (or focus). But \"c\" does not appear in the standard equation of\r\n" );
document.write( "a hyperbola. We calculate \"b2\" by the Pythagorean theorem:\r\n" );
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document.write( "The center is (0,0), so h=0, k=0, a2=4^2=16, b2=3^2=9.\r\n" );
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document.write( "Substitute in\r\n" );
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document.write( "Edwin
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document.write( "![\"\"](\"/images/stars/stars-13.gif\")
