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[行业讨论] 一个难倒大学生的三角函数题,考考大家

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发表于 2008-12-28 01:34 | 显示全部楼层 |阅读模式
< class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">(</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt"><FONT face="Times New Roman">2R</FONT></SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">)</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体">&sup2;<SPAN lang=EN-US>=125</SPAN>&sup2;<SPAN lang=EN-US>+</SPAN>(<SPAN lang=EN-US>150-R</SPAN>)&sup2;</SPAN></P>1 `5 g. }, v6 R# T9 S  H  [2 u8 }
< class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体"></SPAN>&nbsp;</P>& a$ I5 v/ \/ }; {2 j
< class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体"></SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o:p><FONT face=宋体>求R=?</FONT></o:p></SPAN></P>
发表于 2008-12-28 08:08 | 显示全部楼层
不是吧,你把现在的大学生当白哥。
发表于 2008-12-28 14:36 | 显示全部楼层
除了用计算器还有更好的方法吗,等效的?
发表于 2008-12-29 02:38 | 显示全部楼层
<H2>% r0 Q* L$ k/ s8 X/ x" _7 d
< class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-pagination: widow-orphan; mso-outline-level: 2" align=center><SPAN style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">一个难倒大学生的三角函数题,考考大家<SPAN lang=EN-US><?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o:p></o:p></SPAN></SPAN></P>1 y" f# Q! ]8 f* X$ h& L! {9 d
< class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-line-height-alt: 19.2pt" align=center><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">(</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">2R</FONT></SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">)</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">&sup2;<SPAN lang=EN-US>=125</SPAN>&sup2;<SPAN lang=EN-US>+</SPAN>(<SPAN lang=EN-US>150-R</SPAN>)&sup2;</SPAN><SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt"><o:p></o:p></SPAN></P>
& S% Y1 ]- Y. s# W< class=MsoNormal style="MARGIN: 0cm 0cm 0pt; LINE-HEIGHT: 19.2pt; TEXT-ALIGN: center; mso-pagination: widow-orphan" align=center><SPAN lang=EN-US style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">&nbsp;<o:p></o:p></SPAN></P>
' L) R" f8 n: K- z' C3 f2 ?< class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center; mso-pagination: widow-orphan; mso-line-height-alt: 19.2pt" align=center><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">求<SPAN lang=EN-US>R=</SPAN>?<SPAN lang=EN-US><o:p></o:p></SPAN></SPAN></P>
, P3 t. s# W. s! w' [( X< class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是这样求解的</SPAN><SPAN lang=EN-US><FONT face="Times New Roman">,</FONT></SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">公式可看作</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">(</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">2R</FONT></SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">)</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">&sup2;<SPAN lang=EN-US>-</SPAN>(<SPAN lang=EN-US>150-R</SPAN>)&sup2;<SPAN lang=EN-US>=125</SPAN>&sup2;又把</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">2R</FONT></SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-font-kerning: 0pt">看作</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">a<SPAN style="mso-spacerun: yes">&nbsp;&nbsp; </SPAN>,</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt"> 150-R</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">看作<SPAN lang=EN-US>b<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>125</SPAN>&sup2;看作<SPAN lang=EN-US>c</SPAN>这样就有公式<SPAN lang=EN-US>.a</SPAN>&sup2;<SPAN lang=EN-US>-b</SPAN>&sup2;<SPAN lang=EN-US>=c</SPAN>而<SPAN lang=EN-US>a</SPAN>&sup2;<SPAN lang=EN-US>-b</SPAN>&sup2;<SPAN lang=EN-US>=(a+b)(a-b)</SPAN>从而得到<SPAN lang=EN-US>(</SPAN></SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman">2R+</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">150-R)(</SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; mso-font-kerning: 0pt"><FONT face="Times New Roman"> 2R</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">-150+R)= 125</SPAN><SPAN style="FONT-SIZE: 36pt; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体; mso-font-kerning: 0pt">&sup2;<SPAN lang=EN-US><SPAN style="mso-spacerun: yes">&nbsp; </SPAN></SPAN>从而<SPAN lang=EN-US>3R</SPAN>&sup2;<SPAN lang=EN-US>-300R-2X150</SPAN>&sup2;<SPAN lang=EN-US>=0</SPAN>解之<SPAN lang=EN-US>R=?????</SPAN>时间有限自己解出来吧</SPAN></P></H2>
发表于 2008-12-29 15:24 | 显示全部楼层
恩,有难度
发表于 2008-12-29 15:25 | 显示全部楼层
4楼的搞错了
发表于 2008-12-29 15:52 | 显示全部楼层

哪位大哥指点一下

哪位大哥指点一下
发表于 2009-4-15 15:23 | 显示全部楼层
我看都看不懂
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发表于 2009-4-22 21:02 | 显示全部楼层
看不懂里面是什么
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