document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1205097>Question 1205097</A>: <I><SPAN STYLE=\"word-break: break-all;\"> So I tried calculating the Cotangent of <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=pi+%2F+2 ALIGN=MIDDLE  ALT=\"pi+%2F+2\"   DISABLED_style= \"max-width:90%; height:auto;\" > (90 degrees). The answer is 0, but my scientific calculator (Casio Fx300ES Plus) didn't say that. \r<BR>\n" );
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document.write( "I inputted: <BR>\n" );
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document.write( "But I got a Math ERROR. The answer is 0, not undefined? Why's that? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #841728 by </B><A HREF=/tutors/aboutme.mpl?userid=math_tutor2020><B>math_tutor2020(3817)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=math_tutor2020><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=841728\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=black size=3><BR>\n" );
document.write( "I'm not 100% certain if this is the case with Casio calculators, but check out this page here<BR>\n" );
document.write( "<a  rel=nofollow HREF=\"https://stackoverflow.com/questions/345085/how-do-trigonometric-functions-work\">https://stackoverflow.com/questions/345085/how-do-trigonometric-functions-work</a>\r<BR>\n" );
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document.write( "The CORDIC algorithm can be used to compute cos(pi/2) and sin(pi/2)<BR>\n" );
document.write( "Since pi/2 is a common angle, likely your calculator will retrieve the following from a lookup table.<BR>\n" );
document.write( "cos(pi/2) = 0 <BR>\n" );
document.write( "sin(pi/2) = 1\r<BR>\n" );
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document.write( "Then under the hood your calculator would then use the identity that<BR>\n" );
document.write( "cot = cos/sin<BR>\n" );
document.write( "So you'll have 0 up top and 1 down below. <BR>\n" );
document.write( "The ultimate result is 0. This is the correct value of cot(pi/2)\r<BR>\n" );
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document.write( "Why does your calculator throw an error when computing 1/tan?<BR>\n" );
document.write( "Because tan = sin/cos, and cos(pi/2) = 0.<BR>\n" );
document.write( "So tan(pi/2) = 1/0 = undefined<BR>\n" );
document.write( "tan(pi/2) being undefined leads to the 1/tan also undefined (even though it should be 0).\r<BR>\n" );
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document.write( "Technically what's going on is that as x gets closer to pi/2 from the left, tan(x) approaches positive infinity. <BR>\n" );
document.write( "Stuff of the form 1/tan will approach 0 because you have something like 1/(some really large number). <BR>\n" );
document.write( "If you haven't covered limits yet then don't worry. <BR>\n" );
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