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<BR><A NAME="1195482"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><A HREF="math.html#1195485" >Math.asin</A>, <A HREF="math.html#1195541" >Math.atan</A>, <A HREF="math.html#1195597" >Math.atan2</A>, <A HREF="math.html#1195695" >Math.cos</A>, <A HREF="math.html#1197769" >Math.sin</A>, <A HREF="math.html#1194346" >Math.tan</A></zparagraph></FONT><P><BR><P><A NAME="1195485"> </A><A NAME="asin"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><B><zrefhead2>asin</zrefhead2></B></FONT><P><A NAME="1195502"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Returns the arcsine (in radians) of a number.<BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B></B></FONT><BR><BR> <TR> <TD VALIGN=TOP><P><A NAME="1195488"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Method of</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195493"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><A HREF="math.html#1193138" >Math</A></ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP COLSPAN=2 ROWSPAN=1><P><A NAME="1195495"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Static</I></ztabletext></FONT></TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1195499"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Implemented in</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195501"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.0, NES 2.0</ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1201682"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>ECMA version</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1201684"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>ECMA-262</ztabletext></FONT> </TD> </TR></TABLE><P></zparagraph></FONT><P><BR><A NAME="1195503"> </A><A NAME="Syntax"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Syntax</zrefheader></B></FONT><BR><A NAME="1195504"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>asin(<I>x</I>)</zcodeline></FONT><P><BR><A NAME="1195505"> </A><A NAME="Parameters"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Parameters</zrefheader></B></FONT><BR><A NAME="1195511"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B></B></FONT><BR><BR> <TR> <TD VALIGN=TOP><A NAME="1195508"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>x</zcodeline></FONT><P> </TD> <TD VALIGN=TOP><P><A NAME="1195510"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>A number</ztabletext></FONT> </TD> </TR></TABLE><P></zparagraph></FONT><P><BR><A NAME="1195512"> </A><A NAME="Description"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Description</zrefheader></B></FONT><BR><A NAME="1195513"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The <FONT FACE="courier, couriernew, monospaced size">asin</FONT> method returns a numeric value between -pi/2 and pi/2 radians. If the value of <FONT FACE="courier, couriernew, monospaced size">number</FONT> is outside this range, it returns <FONT FACE="courier, couriernew, monospaced size">NaN</FONT>.</zparagraph></FONT><P><A NAME="1195514"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Because <FONT FACE="courier, couriernew, monospaced size">asin</FONT> is a static method of <FONT FACE="courier, couriernew, monospaced size">Math</FONT>, you always use it as <FONT FACE="courier, couriernew, monospaced size">Math.asin()</FONT>, rather than as a method of a <FONT FACE="courier, couriernew, monospaced size">Math</FONT> object you created.</zparagraph></FONT><P><BR><A NAME="1195515"> </A><A NAME="Examples"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Examples</zrefheader></B></FONT><BR><A NAME="1195516"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following function returns the arcsine of the variable <FONT FACE="courier, couriernew, monospaced size">x</FONT>:</zparagraph></FONT><P><A NAME="1195517"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>function getAsin(x) {<br> return Math.asin(x)<br>}</zcodeline></FONT><P><A NAME="1195518"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>If you pass <FONT FACE="courier, couriernew, monospaced size">getAsin</FONT> the value 1, it returns 1.570796326794897 (pi/2); if you pass it the value 2, it returns <FONT FACE="courier, couriernew, monospaced size">NaN</FONT> because 2 is out of range.</zparagraph></FONT><P><BR><A NAME="1195519"> </A><A NAME="See also"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>See also</zrefheader></B></FONT><BR><A NAME="1195538"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><A HREF="math.html#1195429" >Math.acos</A>, <A HREF="math.html#1195541" >Math.atan</A>, <A HREF="math.html#1195597" >Math.atan2</A>, <A HREF="math.html#1195695" >Math.cos</A>, <A HREF="math.html#1197769" >Math.sin</A>, <A HREF="math.html#1194346" >Math.tan</A></zparagraph></FONT><P><BR><P><A NAME="1195541"> </A><A NAME="atan"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><B><zrefhead2>atan</zrefhead2></B></FONT><P><A NAME="1195558"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Returns the arctangent (in radians) of a number.<BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B></B></FONT><BR><BR> <TR> <TD VALIGN=TOP><P><A NAME="1195544"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Method of</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195549"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><A HREF="math.html#1193138" >Math</A></ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP COLSPAN=2 ROWSPAN=1><P><A NAME="1195551"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Static</I></ztabletext></FONT></TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1195555"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Implemented in</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195557"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.0, NES 2.0</ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1201695"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>ECMA version</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1201697"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>ECMA-262</ztabletext></FONT> </TD> </TR></TABLE><P></zparagraph></FONT><P><BR><A NAME="1195559"> </A><A NAME="Syntax"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Syntax</zrefheader></B></FONT><BR><A NAME="1195560"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>atan(<I>x</I>)</zcodeline></FONT><P><BR><A NAME="1195561"> </A><A NAME="Parameters"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Parameters</zrefheader></B></FONT><BR><A NAME="1195567"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B></B></FONT><BR><BR> <TR> <TD VALIGN=TOP><A NAME="1195564"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>x</zcodeline></FONT><P> </TD> <TD VALIGN=TOP><P><A NAME="1195566"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>A number</ztabletext></FONT> </TD> </TR></TABLE><P></zparagraph></FONT><P><BR><A NAME="1195568"> </A><A NAME="Description"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Description</zrefheader></B></FONT><BR><A NAME="1195569"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The <FONT FACE="courier, couriernew, monospaced size">atan</FONT> method returns a numeric value between -pi/2 and pi/2 radians.</zparagraph></FONT><P><A NAME="1195570"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Because <FONT FACE="courier, couriernew, monospaced size">atan</FONT> is a static method of <FONT FACE="courier, couriernew, monospaced size">Math</FONT>, you always use it as <FONT FACE="courier, couriernew, monospaced size">Math.atan()</FONT>, rather than as a method of a <FONT FACE="courier, couriernew, monospaced size">Math</FONT> object you created.</zparagraph></FONT><P><BR><A NAME="1195571"> </A><A NAME="Examples"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Examples</zrefheader></B></FONT><BR><A NAME="1195572"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following function returns the arctangent of the variable <FONT FACE="courier, couriernew, monospaced size">x</FONT>:</zparagraph></FONT><P><A NAME="1195573"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>function getAtan(x) {<br> return Math.atan(x)<br>}</zcodeline></FONT><P><A NAME="1195574"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>If you pass <FONT FACE="courier, couriernew, monospaced size">getAtan</FONT> the value 1, it returns 0.7853981633974483; if you pass it the value .5, it returns 0.4636476090008061.</zparagraph></FONT><P><BR><A NAME="1195575"> </A><A NAME="See also"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>See also</zrefheader></B></FONT><BR><A NAME="1195594"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph><A HREF="math.html#1195429" >Math.acos</A>, <A HREF="math.html#1195485" >Math.asin</A>, <A HREF="math.html#1195597" >Math.atan2</A>, <A HREF="math.html#1195695" >Math.cos</A>, <A HREF="math.html#1197769" >Math.sin</A>, <A HREF="math.html#1194346" >Math.tan</A></zparagraph></FONT><P><BR><P><A NAME="1195597"> </A><A NAME="atan2"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><B><zrefhead2>atan2</zrefhead2></B></FONT><P><A NAME="1195614"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Returns the arctangent of the quotient of its arguments.<BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B></B></FONT><BR><BR> <TR> <TD VALIGN=TOP><P><A NAME="1195600"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Method of</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195605"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><A HREF="math.html#1193138" >Math</A></ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP COLSPAN=2 ROWSPAN=1><P><A NAME="1195607"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Static</I></ztabletext></FONT></TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1195611"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>Implemented in</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1195613"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.0, NES 2.0</ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1201757"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext><I>ECMA version</I></ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1201759"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>ECMA-262</ztabletext></FONT> </TD> </TR></TABLE><P></zparagraph></FONT><P><BR><A NAME="1195615"> </A><A NAME="Syntax"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Syntax</zrefheader></B></FONT><BR><A NAME="1195616"></A><FONT FACE="courier, couriernew, monospaced size" SIZE="2"><zcodeline>atan2(<I>y</I>, <I>x</I>)</zcodeline></FONT><P><BR><A NAME="1195617"> </A><A NAME="Parameters"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><zrefheader>Parameters</zrefheader></B>?? 快捷鍵說明
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